Resist composition and method of forming resist pattern

ABSTRACT

A resist composition containing a resin component (A1) having a constitutional unit (a01) derived from a compound represented by General Formulae (a0-1) and one or more compounds selected from the group consisting of a compound (B01) represented by General Formula (b0-1) and a compound (B02) represented by General Formula (b0-2), W 01  represents a polymerizable group-containing group, Ya 01  represents a single bond or the like, Rx 01  represents an acid dissociable group, R b1  and R b4  represents an aryl group having a fluorine atom, R b2 , R b3 , and R b5  represents an aryl group or the like which may have a substituent, and X 01   −  and X 02   −  represents a counter anion

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a resist composition and a method of forming a resist pattern.

Priority is claimed on Japanese Patent Application No. 2020-175440, filed on Oct. 19, 2020, Japanese Patent Application No. 2021-143257, filed on Sep. 2, 2021 and Japanese Patent Application No. 2021-161666, filed on Sep. 30, 2021, the entire contents of which are incorporated herein by reference.

Description of Related Art

In recent years, in the production of semiconductor elements and liquid crystal display elements, advances in lithography techniques have led to a rapid progress in the field of pattern miniaturization. Typically, these miniaturization techniques involve shortening the wavelength (increasing the energy) of the light source for exposure.

Resist materials for use with these types of light sources for exposure require lithography characteristics such as a high resolution capable of reproducing patterns of minute dimensions, and a high level of sensitivity to these types of light sources for exposure.

As a resist material that satisfies these requirements, a chemically amplified resist composition which contains a base material component exhibiting changed solubility in a developing solution under action of acid, and an acid generator component that generating acid upon exposure has been conventionally used.

In the chemically amplified resist composition, a resin having a plurality of constitutional units is generally used for improving the lithography characteristics and the like.

In addition, in the formation of the resist pattern, the behavior of an acid generated from an acid generator component upon exposure is considered as one factor that has a great influence on lithography characteristics.

For example, Patent Document 1 describes that an onium salt-based acid generator having a sulfonium cation to which a sulfonyl group is introduced is used to increase sensitivity.

CITATION LIST Patent Document

[Patent Document 1] Japanese Patent No. 4411042

SUMMARY OF THE INVENTION

With the further progress of lithography technology and the miniaturization of a resist pattern, for example, it is aimed to form a fine pattern of several tens of nanometers in lithography by EUV and EB. As the resist pattern size becomes smaller as described above, it is required to improve each of the lithography characteristics such as sensitivity, resolution, and roughness without the trade-off thereof.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a resist composition having good sensitivity, good resolution, and good roughness reducing property, and a method of forming a resist pattern using the resist composition.

In order to achieve the above-described object, the present invention employs the following configurations.

That is, the first aspect according to the present invention is a resist composition generating acid upon exposure and exhibits changed solubility in a developing solution under action of acid, which contains a resin component (A1) exhibiting changed solubility in a developing solution under action of acid and an acid generator component (B) generating acid upon exposure, in which the resin component (A1) has a constitutional unit (a01) derived from a compound represented by General Formula (a0-1) and the acid generator component (B) contains one or more compounds selected from the group consisting of a compound (B01) represented by General Formula (b0-1) and a compound (B02) represented by General Formula (b0-2).

[In the formula, W⁰¹ represents a polymerizable group-containing group. Ya⁰¹ represents a single bond or a divalent linking group. Rx⁰¹ represents an acid dissociable group, q represents an integer in a range of 0 to 3. n represents an integer of 1 or more. However, n≤q×2+4 is satisfied.]

[In General Formula (b0-1), R^(b1) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group. R^(b2) and R^(b3) each independently represent an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent. Two of R^(b1) to R^(b3) may be bonded to each other to form a ring together with a sulfur atom in the formula. X₀f represents a counter anion.

In General Formula (b0-2), R^(b4) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group. R^(b5) represents an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent. X₀₂ ⁻ represents a counter anion.]

The second aspect according to the present invention is a method of forming a resist pattern, including a step of forming a resist film on a support using the resist composition according to the first aspect, a step of exposing the resist film, and a step of developing the exposed resist film to form a resist pattern.

According to the present invention, it is possible to provide a resist composition having good sensitivity, good resolution, and roughness reducing property, and a method of forming a resist pattern using the resist composition.

DETAILED DESCRIPTION OF THE INVENTION

In the present specification and the scope of the present claims, the “aliphatic” is a relative concept used with respect to the “aromatic” and defines a group, a compound, or the like, which has no aromaticity.

The term “alkyl group” includes a linear, a branched, and a cyclic monovalent saturated hydrocarbon groups, unless otherwise specified. The same applies to the alkyl group in an alkoxy group.

The term “alkylene group” includes a linear, a branched, and a cyclic divalent saturated hydrocarbon group, unless otherwise specified.

Examples of the “halogen atom” include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

The “constitutional unit” indicates a monomer unit that constitutes a polymeric compound (a resin, a polymer, or a copolymer).

In a case where “may have a substituent” is described, both of a case where a hydrogen atom (—H) is substituted with a monovalent group and a case where a methylene group (—CH₂—) is substituted with a divalent group are included.

The term “exposure” is used as a general concept that includes irradiation with any form of radiation.

The term “acid decomposable group” indicates a group in which at least part of bonds in the structure of the acid decomposable group can be cleaved under action of acid.

Examples of the acid decomposable group having a polarity which is increased under action of acid include groups which are decomposed under action of acid to generate a polar group.

Examples of the polar group include a carboxy group, a hydroxyl group, an amino group, and a sulfo group (—SO₃H).

More specific examples of the acid decomposable group include a group (for example, a group obtained by protecting a hydrogen atom of the OH-containing polar group with an acid dissociable group) obtained by protecting the above-described polar group with an acid dissociable group.

The “acid dissociable group” indicates any one of (i) a group in which a bond between the acid dissociable group and an atom adjacent to the acid dissociable group can be cleaved under action of acid; and (ii) a group in which a part of bonds are cleaved under action of acid, and then a decarboxylation reaction further occurs, thereby cleaving the bond between the acid dissociable group and the atom adjacent to the acid dissociable group.

It is necessary that the acid dissociable group that constitutes the acid decomposable group be a group that exhibits a lower polarity than the polar group generated by the dissociation of the acid dissociable group.

Thus, in a case where the acid dissociable group is dissociated under action of acid, a polar group exhibiting a higher polarity than the acid dissociable group is generated, thereby increasing the polarity. As a result of the above, the polarity of the entire component (A1) is increased. With the increase in the polarity, the solubility in a developing solution relatively changes. The solubility in a developing solution is increased in a case where the developing solution is an alkali developing solution, whereas the solubility in a developing solution is decreased in a case where the developing solution is an organic developing solution.

The “base material component” is an organic compound having a film-forming ability. The organic compounds used as the base material component are roughly classified into a non-polymer and a polymer. As the non-polymer, those having a molecular weight of 500 or more and less than 4,000 are usually used. Hereinafter, a “low molecular weight compound” refers to a non-polymer having a molecular weight of 500 or more and less than 4,000. As the polymer, those having a molecular weight of 1,000 or more are usually used. Hereinafter, a “resin”, a “polymeric compound”, or a “polymer” refers to a polymer having a molecular weight of 1,000 or more. As the molecular weight of the polymer, a polystyrene-equivalent weight average molecular weight determined by gel permeation chromatography (GPC) is used.

A “constitutional unit derived from” means a constitutional unit that is formed by the cleavage of a multiple bond between carbon atoms, for example, an ethylenic double bond.

In the “acrylic acid ester”, the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent. The substituent (R^(αx)) that is substituted for the hydrogen atom bonded to the carbon atom at the a-position is an atom other than the hydrogen atom, or a group. Further, an itaconic acid diester in which the substituent (R^(αx)) is substituted with a substituent having an ester bond or an α-hydroxyacryl ester in which the substituent (R^(αx)) is substituted with a hydroxyalkyl group or a group obtained by modifying a hydroxyl group of the hydroxyalkyl group can be mentioned as the acrylic acid ester. A carbon atom at the a-position of acrylic acid ester indicates the carbon atom bonded to the carbonyl group of acrylic acid unless otherwise specified.

Hereinafter, an acrylic acid ester obtained by substituting a hydrogen atom bonded to the carbon atom at the α-position with a substituent is also referred to as an α-substituted acrylic acid ester.

The “derivative” includes a compound obtained by substituting a hydrogen atom at the α-position of an object compound with another substituent such as an alkyl group or a halogenated alkyl group; and a derivative thereof. Examples of the derivative thereof include a derivative obtained by substituting the hydrogen atom of a hydroxyl group of an object compound in which a hydrogen atom at the α-position may be substituted with a substituent, with an organic group; and a derivative obtained by bonding a substituent other than the hydroxyl group to an object compound in which a hydrogen atom at the α-position may be substituted with a substituent. The α-position refers to the first carbon atom adjacent to the functional group unless otherwise specified.

Examples of the substituent that is substituted for the hydrogen atom at the α-position of hydroxystyrene include the same one as R^(αx).

In the present specification and the scope of the present claims, asymmetric carbon atoms may be present, and thus enantiomers or diastereomers may be present depending on the structures represented by the chemical formula. In that case, these isomers are represented by one chemical formula. These isomers may be used alone or in the form of a mixture.

(Resist Composition)

The resist composition according to the present embodiment is a resist composition that generates acid upon exposure and exhibits changed solubility in a developing solution under action of acid.

Such a resist composition contains a base material component (A) (hereinafter, also referred to as a “component (A)”) exhibiting changed solubility in a developing solution under action of acid, and an acid generator component (B) generating acid upon exposure (hereinafter, also referred to as a “component (B)”).

In a case where a resist film is formed using the resist composition according to the present embodiment and the formed resist film is subjected to selective exposure, an acid is generated from the component (B) at exposed portions of the resist film, and the generated acid acts on the component (A) to change the solubility of the component (A) in a developing solution, whereas the solubility of the component (A) in a developing solution is not changed at unexposed portions of the resist film, thereby that generates the difference in solubility in the developing solution between exposed portions and unexposed portions of the resist film.

The resist composition according to the present embodiment may be a positive-tone resist composition or a negative-tone resist composition.

Further, in the formation of a resist pattern, the resist composition according to the present embodiment may be applied to an alkali developing process using an alkali developing solution in the developing treatment, or a solvent developing process using an organic developing solution in the developing treatment.

That is, the resist composition according to the present embodiment is a “positive-tone resist composition for an alkali developing process” that forms a positive-tone resist pattern in an alkali developing process and is a “negative-tone resist composition for a solvent developing process” that forms a negative-tone resist pattern in a solvent developing process.

<Component (A)>

In the resist composition according to the present embodiment, the component (A) contains a resin component (A1) (hereinafter, also referred to as a “component (A1)”) exhibiting changed solubility in a developing solution under action of acid, and the resin component (A1) has a constitutional unit (a01) derived from a compound represented by General Formula (a0-1).

As the component (A), at least the component (A1) is used, and at least one of another polymeric compound and another low molecular weight compound may be used in combination with the component (A1).

In the resist composition according to the present embodiment, the component (A) may be used alone or in a combination of two or more kinds thereof.

In Regard to Component (A1)

The component (A1) has a constitutional unit (a01).

<<Constitutional Unit (a01)>>

The constitutional unit (a01) is a constitutional unit derived from a compound represented by General Formula (a0-1).

[In the formula, W⁰¹ represents a polymerizable group-containing group. Ya⁰¹ represents a single bond or a divalent linking group. Rx⁰¹ represents an acid dissociable group, q represents an integer in a range of 0 to 3. n represents an integer of 1 or more. However, n≤q×2+4 is satisfied.]

In General Formula (a0-1), W⁰¹ represents a polymerizable group-containing group.

The “polymerizable group” as W⁰¹ is a group that enables a compound having the polymerizable group to be polymerized by radical polymerization or the like, and includes a group containing a multiple bond between carbon atoms, such as an ethylenic double bond.

In the constitutional unit (a01), the multiple bonds in the polymerizable group are cleaved to form a main chain.

Examples of the polymerizable group as W⁰¹ include a vinyl group, an allyl group, acryloyl group, a methacryloyl group, a fluorovinyl group, a difluorovinyl group, a trifluorovinyl group, a difluorotrifluoromethylvinyl group, a trifluoroallyl group, a perfluoroallyl group, a trifluoromethylacryloyl group, a nonylfluorobutylacryloyl group, a vinyl ether group, a fluorine-containing vinyl ether group, an allyl ether group, a fluorine-containing allyl ether group, a styryl group, and a vinylnaphthyl group, a fluorine-containing styryl group, a fluorine-containing vinylnaphthyl group, a norbornyl group, a fluorine-containing norbornyl group, and a silyl group.

The “polymerizable group-containing group” as W⁰¹ may be a group composed of only a polymerizable group, or a group composed of a polymerizable group and a group other than the polymerizable group. Examples of the group other than the polymerizable group include a divalent hydrocarbon group which may have a substituent and a divalent linking group containing a hetero atom.

Divalent Hydrocarbon Group which May have Substituent:

In a case where the group other than the polymerizable group represents a divalent hydrocarbon group which may have a substituent, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

Aliphatic Hydrocarbon Group as a Group Other than the Polymerizable Group

The aliphatic hydrocarbon group indicates a hydrocarbon group that has no aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated. In general, it is preferable that the aliphatic hydrocarbon group is saturated.

Examples of the aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, and an aliphatic hydrocarbon group containing a ring in the structure thereof.

Linear or Branched Aliphatic Hydrocarbon Group

The linear aliphatic hydrocarbon group described above preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

The linear aliphatic hydrocarbon group is preferably a linear alkylene group, and specific examples thereof include a methylene group [—CH₂—], an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group described above preferably has 2 to carbon atoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms.

The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof include alkylalkylene groups, for example, alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

The linear or branched aliphatic hydrocarbon group may have or may not have a substituent. Examples of the substituent include a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, which has been substituted with a fluorine atom, and a carbonyl group.

Aliphatic Hydrocarbon Group Containing Ring in Structure Thereof

Examples of the aliphatic hydrocarbon group containing a ring in the structure thereof include a cyclic aliphatic hydrocarbon group which may have a substituent containing a hetero atom in the ring structure thereof (a group obtained by removing two hydrogen atoms from an aliphatic hydrocarbon ring), a group obtained by bonding the cyclic aliphatic hydrocarbon group to the terminal of a linear or branched aliphatic hydrocarbon group, and a group obtained by interposing the cyclic aliphatic hydrocarbon group in a linear or branched aliphatic hydrocarbon group. Examples of the linear or branched aliphatic hydrocarbon group include the same ones as those described above.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms and more preferably 3 to 12 carbon atoms.

The cyclic aliphatic hydrocarbon group may be a polycyclic group or a monocyclic group. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a polycycloalkane, and the polycycloalkane is preferably a group having 7 to 12 carbon atoms. Specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

The cyclic aliphatic hydrocarbon group may have or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.

The alkoxy group as the substituent is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is preferable.

Examples of the halogenated alkyl group as the substituent include a group obtained by substituting part or all hydrogen atoms in the above-described alkyl groups with the above-described halogen atoms.

In the cyclic aliphatic hydrocarbon group, part of carbon atoms constituting the ring structure thereof may be substituted with a substituent containing a hetero atom. The substituent containing a hetero atom is preferably —O—, —C(═O)—O—, —S—, —S(═O)₂—, or —S(═O)₂—O—.

Aromatic Hydrocarbon Group as a Group Other than the Polymerizable Group

The aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.

The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having (4n+2) π electrons, and may be monocyclic or polycyclic. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Here, the number of carbon atoms in a substituent is not included in the number of carbon atoms. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting the above-described aromatic hydrocarbon ring with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocyclic ring include a pyridine ring and a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group (an arylene group or a heteroarylene group) obtained by removing two hydrogen atoms from the above-described aromatic hydrocarbon ring or the above-described aromatic heterocyclic ring; a group obtained by removing two hydrogen atoms from an aromatic compound (for example, biphenyl or fluorene) having two or more aromatic rings; and a group (for example, a group obtained by further removing one hydrogen atom from an aryl group in the arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group) obtained by substituting one hydrogen atom of a group (an aryl group or a heteroaryl group) obtained by removing one hydrogen atom from the above aromatic hydrocarbon ring or the above aromatic heterocyclic ring, with an alkylene group. The alkylene group bonded to the aryl group or the heteroaryl group preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably 1 carbon atom.

In the aromatic hydrocarbon group, a hydrogen atom contained in the aromatic hydrocarbon group may be substituted with a substituent. For example, the hydrogen atom bonded to the aromatic ring in the aromatic hydrocarbon group may be substituted with a substituent. Examples of substituents include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and most preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.

Examples of the alkoxy group, the halogen atom, and the halogenated alkyl group, as the substituent, include the same groups as those exemplified as the substituent that is substituted for a hydrogen atom contained in the cyclic aliphatic hydrocarbon group.

Divalent Linking Group Containing Hetero Atom:

In a case where the group other than the polymerizable group represents a divalent linking group containing a hetero atom, preferred examples of the linking group include —O—, —C(═O)—O—, —C(═O)—, —O—C(═O)—O— —C(═O)—NH—, —NH—, —NH—C(═NH)—(H may be substituted with a substituent such as an alkyl group, an acyl group, or the like), —S—, —S(═O)₂—, —S(═O)₂—O—, and a group represented by General Formula: —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—, —[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²— or —Y²¹—S(═O)₂—O—Y²²— [in the formulae, Y²¹ and Y²² each independently represent a divalent hydrocarbon group which may have a substituent, O represents an oxygen atom, and m″ represents an integer in a range of 0 to 3].

In a case where the divalent linking group containing a hetero atom is —C(═O)—NH—, —C(═O)—NH—C(═O)—, —NH—, or —NH—C(═NH)—, H may be substituted with a substituent such as an alkyl group, an acyl group, or the like. The substituent (an alkyl group, an acyl group, or the like) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably 1 to 5 carbon atoms.

In General Formula —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—, —[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²—, or —Y²¹—S(═O)₂—O—Y²²—, Y²¹ and Y²² each independently represent a divalent hydrocarbon group which may have a substituent. Examples of the divalent hydrocarbon group include the same ones as those (the divalent hydrocarbon groups which may have a substituent) mentioned in the explanation of the above-described divalent linking group.

Y²¹ is preferably a linear aliphatic hydrocarbon group, more preferably a linear alkylene group, still more preferably a linear alkylene group having 1 to 5 carbon atoms, and particularly preferably a methylene group or an ethylene group.

Y²² is preferably a linear or branched aliphatic hydrocarbon group and more preferably a methylene group, an ethylene group, or an alkylmethylene group. The alkyl group in the alkylmethylene group is preferably a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group.

In the group represented by General Formula —[Y²¹—C(═O)—O]_(m″)—Y²²—, m″ represents an integer in a range of 0 to 3, preferably an integer in a range of 0 to 2, more preferably 0 or 1, and particularly preferably 1. In other words, it is particularly preferable that the group represented by General Formula —[Y²¹—C(═O)—O]_(m″)—Y²²— represents a group represented by General Formula —Y²¹—C(═O)—O—Y²²—. Among them, a group represented by Formula —(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ represents an integer in a range of 1 to 10, preferably an integer in a range of 1 to 8, more preferably an integer in a range of 1 to 5, still more preferably 1 or 2, and most preferably 1. b′ represents an integer in a range of 1 to 10, preferably an integer in a range of 1 to 8, more preferably an integer in a range of 1 to 5, still more preferably 1 or 2, and most preferably 1.

Suitable examples of W⁰¹ include a group represented by a chemical formula: C(R^(X11))(R^(X12))═C(R^(X13))-Ya^(x0).

In the chemical formula, R^(x11), R^(X12), and R^(X13) each represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms, and Ya^(x0) represents a single bond or a divalent linking group.

The alkyl group having 1 to 5 carbon atoms as R^(x11), R^(X12), and R^(X13) is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. The halogenated alkyl group having 1 to 5 carbon atoms is a group obtained by substituting part or all hydrogen atoms in the alkyl group having 1 to 5 carbon atoms with a halogen atom. The halogen atom is particularly preferably a fluorine atom.

Among these, R^(x11) and R^(X12) are each preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and in terms of industrial availability, a hydrogen atom or a methyl group is more preferable, and a hydrogen atom is particularly preferable.

In addition, R^(X13) is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and in terms of industrial availability, a hydrogen atom or a methyl group is more preferable, and a hydrogen atom is particularly preferable.

The divalent linking group as Ya^(x0) is not particularly limited, and suitable examples thereof include a divalent hydrocarbon group which may have a substituent and a divalent linking group having a hetero atom, each of which is the same as that described above.

Among the above, Ya^(x0) is preferably an ester bond [—C(═O)—O— or —O—C(═O)—], an ether bond (—O—), a linear or branched alkylene group, an aromatic hydrocarbon group, or a combination thereof, or a single bond. Among the above, Ya^(x0) is more preferably an ester bond [—C(═O)—O— or —O—C(═O)—], a combination of an ester bond [—C(═O)—O— or —O—C(═O)—] with a linear alkylene group or a single bond, and still more preferably an ester bond [—C(═O)—O— or —O—C(═O)—] or a single bond.

In General Formula (a0-1), Ya⁰¹ represents a single bond or a divalent linking group. The divalent linking group as Ya⁰¹ is not particularly limited, and suitable examples thereof include a divalent hydrocarbon group which may have a substituent and a divalent linking group having a hetero atom, each of which is the same as that described above.

In General Formula (a0-1), Ya⁰¹ is, among the above, preferably an ester bond [—C(═O)—O— or —O—C(═O)—], an ether bond (—O—), a linear or branched alkylene group, an aromatic hydrocarbon group, or a combination thereof, or a single bond. Among these, Ya⁰¹ is more preferably a combination of an ester bond [—C(═O)—O— or —O—C(═O)—] and a linear alkylene group, or a single bond, and still more preferably a single bond.

In General Formula (a0-1), Rx⁰¹ represents an acid dissociable group.

Specific examples of the acid dissociable group include an “acetal-type acid dissociable group” and a “tertiary alkyl ester-type acid dissociable group” described below.

Acetal-Type Acid Dissociable Group:

Examples of the acid dissociable group for protecting a carboxy group or a hydroxyl group include the acid dissociable group represented by General Formula (a0-r-1) shown below (hereinafter, also referred to as an “acetal-type acid dissociable group”).

[In General Formula (a0-r-1), Ra⁰¹ and Ra⁰² each independently represent a hydrogen atom or an alkyl group. Ra⁰³ represents a hydrocarbon group and may be bonded to any one of Ra⁰¹ or Ra⁰² to form a ring. * represents a bonding site.]

In General Formula (a0-r-1), Ra⁰¹ and Ra⁰² each independently represent a hydrogen atom or an alkyl group.

In General Formula (a0-r-1), it is preferable that at least one of Ra⁰¹ and Ra⁰² represents a hydrogen atom and more preferable that both of them represent a hydrogen atom.

In a case where Ra⁰¹ or Ra⁰² represents an alkyl group, the alkyl group is preferably an alkyl group having 1 to 5 carbon atoms. Specific examples thereof preferably include a linear or branched alkyl group. More specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. Among these, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable.

In General Formula (a0-r-1), Ra⁰¹ and Ra⁰² are each independently, among the above, preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms and more preferably a hydrogen atom or a methyl group.

In General Formula (a0-r-1), examples of the hydrocarbon group as Ra⁰³ include a linear or branched alkyl group and a cyclic hydrocarbon group.

The linear alkyl group has preferably 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and still more preferably 1 or 2 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group. Among these, a methyl group, an ethyl group, or an n-butyl group is preferable, and a methyl group or an ethyl group is more preferable.

The branched alkyl group has preferably 3 to 10 carbon atoms and more preferably 3 to 5 carbon atoms. Specific examples thereof include an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group a 1,1-diethylpropyl group, and a 2,2-dimethylbutyl group, and an isopropyl group is preferable.

In a case where Ra⁰³ represents a cyclic hydrocarbon group, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group and may be a polycyclic group or a monocyclic group.

The aliphatic hydrocarbon group which is a monocyclic group is preferably a group obtained by removing one hydrogen atom from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane.

The aliphatic hydrocarbon group which is a polycyclic group is preferably a group obtained by removing one hydrogen atom from a polycycloalkane. The polycycloalkane preferably has 7 to 12 carbon atoms, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

In a case where the cyclic hydrocarbon group as Ra⁰³ is an aromatic hydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.

The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having (4n+2) π electrons, and may be monocyclic or polycyclic. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms.

Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting the above-described aromatic hydrocarbon ring with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocyclic ring include a pyridine ring and a thiophene ring.

Specific examples of the aromatic hydrocarbon group as Ra⁰³ include a group obtained by removing one hydrogen atom from the above-described aromatic hydrocarbon ring or aromatic heterocyclic ring (an aryl group or a heteroaryl group); a group obtained by removing one hydrogen atom from an aromatic compound having two or more aromatic rings (biphenyl, fluorene or the like); and a group obtained by substituting one hydrogen atom of the above-described aromatic hydrocarbon ring or aromatic heterocyclic ring with an alkylene group (an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group). The number of carbon atoms in the alkylene group bonded to the aromatic hydrocarbon ring or aromatic heterocyclic ring is preferably in a range of 1 to 4, more preferably 1 or 2, and particularly preferably 1.

The cyclic hydrocarbon group as Ra⁰³ may have a substituent. Examples of the substituent include, —R^(P1), —R^(P2)—O—R^(P1), —R^(P2)—CO—R^(P1), —R^(P2)—CO—OR^(P1), —R^(P2)—O—CO—R^(P1), —R^(P2)—OH, —R^(P2)—CN, and —R^(P2)—COOH (hereinafter, these substituents are also collectively referred to as “Ra^(x5)”).

Here, R^(P1) represents a monovalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms, a monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to carbon atoms. In addition, R^(P2) represents a single bond, a divalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms, a divalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms. However, part or all hydrogen atoms contained in the chain-like saturated hydrocarbon group, the aliphatic cyclic saturated hydrocarbon group, and the aromatic hydrocarbon group of R^(P1) and R^(P2) may be substituted with a fluorine atom. In the aliphatic cyclic hydrocarbon group, one or more of the above-described substituents may be included as a single kind, or a plurality of the above-described substituents may be included as one or more respective kinds among the above-described substituents.

Examples of the monovalent chain-like saturated hydrocarbon group having 1 to carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms include monocyclic aliphatic saturated hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, and cyclododecyl group; and polycyclic aliphatic saturated hydrocarbon groups such as a bicyclo[2.2.2]octanyl group, a tricyclo[5.2.1.02,6]decanyl group, a tricyclo [3.3.1.13,7]decanyl group, a tetracyclo[6.2.1.13,6.02,7] dodecanyl group, and an adamantyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms include groups obtained by removing one hydrogen atom from an aromatic hydrocarbon ring such as benzene, biphenyl, fluorene, naphthalene, anthracene, and phenanthrene.

In a case where Ra⁰³ is bonded to any one of Ra⁰¹ or Ra⁰² to form a ring, the cyclic group is preferably a 4-membered to 7-membered ring, and more preferably a 4-membered to 6-membered ring. Specific examples of the cyclic group include a tetrahydropyranyl group and a tetrahydrofuranyl group.

Specific examples of the acetal-type acid dissociable group are shown below. * represents a bonding site.

Tertiary Alkyl Ester-Type Acid Dissociable Group:

Examples of the acid dissociable group for protecting the carboxy group include the acid dissociable group represented by General Formula (a0-r-2) shown below.

Among the acid dissociable groups represented by General Formula (a0-r-2), for convenience, a group which is constituted of alkyl groups is referred to as a “tertiary alkyl ester-type acid dissociable group”.

In General Formula (a0-r-2), Ra⁰⁴ to Ra⁰⁶ each independently represents a hydrocarbon group, where Ra⁰⁵ and Ra⁰⁶ may be bonded to each other to form a ring. * represents a bonding site.]

Examples of the hydrocarbon group as Ra⁰⁴ include a linear or branched alkyl group, a chain-like or cyclic alkenyl group, and a cyclic hydrocarbon group.

Examples of the linear or branched alkyl group and the cyclic hydrocarbon group (the aliphatic hydrocarbon group which is a monocyclic group, the aliphatic hydrocarbon group which is a polycyclic group, or the aromatic hydrocarbon group) as Ra⁰⁴ include the same one as Ra⁰³ described above.

The chain-like or cyclic alkenyl group as Ra⁰⁴ is preferably an alkenyl group having 2 to 10 carbon atoms.

Examples of the hydrocarbon group as Ra⁰⁵ and Ra⁰⁶ include the same one as Ra⁰³.

In a case where Ra⁰⁵ and Ra⁰⁶ are bonded to each other to form a ring, suitable examples thereof include groups represented by General Formula (a0-r2-01), General Formula (a0-r2-02), and General Formula (a0-r2-03).

On the other hand, in a case where Ra⁰⁴ to Ra⁰⁶ are not bonded to each other and represent an independent hydrocarbon group, suitable examples thereof include a group represented by General Formula (a0-r2-04).

[In General Formula (a0-r2-01), Ra⁰⁰¹ represents a linear or branched alkyl group which may have a substituent. Yaa⁰ represents a carbon atom. Xaa⁰ represents a group that forms a cyclic hydrocarbon group together with Yaa⁰. Part or all hydrogen atoms contained in this cyclic hydrocarbon group may be substituted, and part of carbon atoms constituting a ring may be substituted with a hetero atom. * represents a bonding site.

In General Formula (a0-r2-02), Yab⁰ represents a carbon atom. Xab⁰ represents a group that forms a cyclic hydrocarbon group together with Yab⁰. Part or all hydrogen atoms contained in this cyclic hydrocarbon group may be substituted, and part of carbon atoms constituting a ring may be substituted with a hetero atom. Ra⁰⁰² to Ra⁰⁰⁴ each independently represents a hydrogen atom, a monovalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms, or a monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms. Part or all hydrogen atoms contained in the chain-like saturated hydrocarbon group and the aliphatic cyclic saturated hydrocarbon group may be substituted. Two or more of Ra⁰⁰² to Ra⁰⁰⁴ may be bonded to each other to form a cyclic structure. * represents a bonding site.

in General Formula (a0-r2-03), Yac⁰ represents a carbon atom. Xac⁰ represents a group that forms a cyclic hydrocarbon group together with Yac⁰. Part or all hydrogen atoms contained in this cyclic hydrocarbon group may be substituted, and part of carbon atoms constituting a ring may be substituted with a hetero atom. Ra⁰⁰⁵ represents an aromatic hydrocarbon group. Part or all hydrogen atoms contained in the aromatic hydrocarbon group may be substituted, and part of carbon atoms constituting a ring may be substituted with a hetero atom. * represents a bonding site.

In General Formula (a0-r2-04), Ra⁰⁰⁶ and Ra⁰⁰⁷ each independently represent a monovalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms. Part or all hydrogen atoms contained in the chain-like saturated hydrocarbon group may be substituted. Ra⁰⁰⁸ represents a hydrocarbon group which may have a substituent. * represents a bonding site.]

In General Formula (a0-r2-01), Ra⁰⁰¹ represents a linear or branched alkyl group which may have a substituent.

The linear alkyl group has preferably 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and still more preferably 1 or 2 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group. Among these, a methyl group, an ethyl group, or an n-butyl group is preferable, and a methyl group or an ethyl group is more preferable.

The branched alkyl group has preferably 3 to 10 carbon atoms and more preferably 3 to 5 carbon atoms. Specific examples thereof include an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group a 1,1-diethylpropyl group, and a 2,2-dimethylbutyl group, and a tert-butyl group is preferable.

Examples of the substituent which may be contained in the linear or branched alkyl group as Ra⁰⁰¹ include Ra^(x5) described above.

In General Formula (a0-r2-01), Ra⁰⁰¹ represents, among the above, a linear alkyl group having 1 to 5 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms, and more preferably a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 5 carbon atoms.

In General Formula (a0-r2-01), Yaa⁰ represents a carbon atom, and Xaa⁰ represents a group that forms a cyclic hydrocarbon group together with Yaa⁰.

The cyclic hydrocarbon group may be an aliphatic hydrocarbon group, may be a condensed cyclic hydrocarbon group of an aliphatic hydrocarbon group with an aromatic hydrocarbon group, or a may be a polycyclic group or a monocyclic group.

The aliphatic hydrocarbon group which is a monocyclic group is preferably a group obtained by removing two or more hydrogen atoms from a monocycloalkane. The monocycloalkane has preferably 3 to 6 carbon atoms and more preferably 5 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane.

The aliphatic hydrocarbon group which is a polycyclic group is preferably a group obtained by removing two or more hydrogen atoms from a polycycloalkane, where the polycycloalkane preferably has 7 to 12 carbon atoms. Specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

The aromatic hydrocarbon group in the condensed cyclic hydrocarbon group of an aliphatic hydrocarbon group with an aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.

The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having (4n+2) π electrons, and may be monocyclic or polycyclic. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms.

Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting the above-described aromatic hydrocarbon ring with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocyclic ring include a pyridine ring and a thiophene ring.

Specific examples of the condensed cyclic hydrocarbon group of an aliphatic hydrocarbon group with an aromatic hydrocarbon group are shown below.

Part or all hydrogen atoms contained in the cyclic hydrocarbon group may be substituted, and part of carbon atoms constituting a ring may be substituted with a hetero atom.

Specific examples of the substituent that is substituted for part or all hydrogen atoms contained in the cyclic hydrocarbon group include Ra^(x5) described above. In a case where part of carbon atoms constituting a ring is substituted with a hetero atom, the hetero atom includes an oxygen atom, a sulfur atom, and a nitrogen atom.

In General Formula (a0-r2-01), the cyclic hydrocarbon group formed by Xaa⁰ and Yaa⁰ is, among the above, preferably an aliphatic hydrocarbon group which is a monocyclic group or a polycyclic group, more preferably an aliphatic hydrocarbon group which is a monocyclic group, and still more preferably an aliphatic hydrocarbon group which is a monocyclic group having 5 or 6 carbon atoms.

In General Formula (a0-r2-02), Yab⁰ represents a carbon atom, and Xab⁰ represents a group that forms a cyclic hydrocarbon group together with Yab⁰. Examples of this cyclic hydrocarbon group include the same one as the cyclic hydrocarbon group formed by Xaa⁰ and Yaa⁰ described above.

In General Formula (a0-r2-02), Ra⁰⁰² to Ra⁰⁰⁴ each independently represent a hydrogen atom, a monovalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms, or a monovalent aliphatic cyclic saturated hydrocarbon group having 3 to carbon atoms.

Examples of the monovalent chain-like saturated hydrocarbon group having 1 to carbon atoms, as Ra⁰⁰² to Ra⁰⁰⁴, include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, as Ra⁰⁰² to Ra⁰⁰⁴, include monocyclic aliphatic saturated hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, and cyclododecyl group; and polycyclic aliphatic saturated hydrocarbon groups such as a bicyclo[2.2.2]octanyl group, a tricyclo[5.2.1.02,6]decanyl group, a tricyclo[3.3.1.13,7]decanyl group, a tetracyclo[6.2.1.13,6.02,7] dodecanyl group, and an adamantyl group.

Part or all hydrogen atoms contained in the chain-like saturated hydrocarbon group and the aliphatic cyclic saturated hydrocarbon group, as Ra⁰⁰² to Ra⁰⁰⁴, may be substituted with a substituent. Specific examples of the substituent that is substituted for part or all hydrogen atoms contained in the chain-like saturated hydrocarbon group and the aliphatic cyclic saturated hydrocarbon group include Ra^(x5) described above. In a case where part of carbon atoms constituting a ring is substituted with a hetero atom, the hetero atom includes an oxygen atom, a sulfur atom, and a nitrogen atom.

Examples of the group containing a carbon-carbon double bond generated by forming a cyclic structure, which is obtained by bonding two or more of Ra⁰⁰² to Ra⁰⁰⁴ to each other, include a cyclopentenyl group, a cyclohexenyl group, a methylcyclopentenyl group, a methylcyclohexenyl group, a cyclopentylideneethenyl group, and a cyclohexylideneethenyl group. Among these, a cyclopentenyl group, a cyclohexenyl group, and a cyclopentylideneethenyl group are preferable from the viewpoint of easy synthesis.

In General Formula (a0-r2-02), Ra⁰⁰² to Ra⁰⁰⁴ each independently preferably represents, among the above, a hydrogen atom or a monovalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrogen atom, a methyl group, or an ethyl group, and still more preferably a hydrogen atom.

In General Formula (a0-r2-03), Yac⁰ represents a carbon atom, and Xac⁰ represents a group that forms a cyclic hydrocarbon group together with Yac⁰. Examples of this cyclic hydrocarbon group include the same one as the cyclic hydrocarbon group formed by Xaa⁰ and Yaa⁰ described above.

In General Formula (a0-r2-03), Ra⁰⁰⁵ as an aromatic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from an aromatic hydrocarbon ring having 6 to 15 carbon atoms, more preferably a group obtained by removing one or more hydrogen atoms from benzene, naphthalene, anthracene, or phenanthrene, still more preferably a group obtained by removing one or more hydrogen atoms from benzene or naphthalene, particularly preferably a group obtained by removing one or more hydrogen atoms from benzene.

Part or all hydrogen atoms contained in the aromatic hydrocarbon group may be substituted, or part of carbon atoms constituting a ring may be substituted with a hetero atom.

Specific examples of the substituent that is substituted for part or all hydrogen atoms contained in the aromatic hydrocarbon group include Ra^(x5) described above. In a case where part of carbon atoms constituting a ring is substituted with a hetero atom, the hetero atom includes an oxygen atom, a sulfur atom, and a nitrogen atom.

In General Formula (a0-r2-04), Ra⁰⁰⁶ and Ra⁰⁰⁷ each independently represent a monovalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms.

Examples of the monovalent chain-like saturated hydrocarbon group having 1 to carbon atoms, as Ra⁰⁰⁶ and Ra⁰⁰⁷, include the same ones as the monovalent chain-like saturated hydrocarbon group having 1 to 10 carbon atoms, as Ra⁰⁰² to Ra⁰⁰⁴, as described above.

In General Formula (a0-r2-04), Ra⁰⁰⁶ and Ra⁰⁰⁷ are, among the above, preferably an alkyl group having 1 to 5 carbon atoms, more preferably a methyl group or an ethyl group, and still more preferably a methyl group.

In a case where the chain-like saturated hydrocarbon groups represented by Ra⁰⁰⁶ and Ra⁰⁰⁷ are substituted, examples of the substituent include the same group as Ra^(x5) described above.

In General Formula (a0-r2-04), Ra⁰⁰⁸ represents a hydrocarbon group which may have a substituent. Examples of the hydrocarbon group as Ra⁰⁰⁸ include a linear or branched alkyl group and a cyclic hydrocarbon group.

The linear alkyl group as Ra⁰⁰⁸ is preferably 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms, and still more preferably 1 or 2 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl group. Among these, a methyl group, an ethyl group, or an n-butyl group is preferable, and a methyl group or an ethyl group is more preferable.

The branched alkyl group as Ra⁰⁰⁸ preferably has 3 to 10 carbon atoms and more preferably 3 to 5 carbon atoms. Specific examples thereof include an isopropyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a neopentyl group a 1,1-diethylpropyl group, and a 2,2-dimethylbutyl group, and an isopropyl group is preferable.

In a case where Ra⁰⁰⁸ represents a cyclic hydrocarbon group, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group and may be a polycyclic group or a monocyclic group.

The aliphatic hydrocarbon group which is a monocyclic group is preferably a group obtained by removing one hydrogen atom from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane.

The aliphatic hydrocarbon group which is a polycyclic group is preferably a group obtained by removing one hydrogen atom from a polycycloalkane. The polycycloalkane preferably has 7 to 12 carbon atoms, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

Examples of the aromatic hydrocarbon group as Ra⁰⁰⁸ include the same one as the aromatic hydrocarbon group as Ra⁰⁰⁵. Among them, Ra⁰⁰⁸ is preferably a group in which one or more hydrogen atoms have been removed from an aromatic hydrocarbon ring having 6 to 15 carbon atoms, more preferably a group in which one or more hydrogen atoms have been removed from benzene, naphthalene, anthracene, or phenanthrene, still more preferably a group in which one or more hydrogen atoms have been removed from benzene, naphthalene, or anthracene, particularly preferably a group in which one or more hydrogen atoms have been removed from naphthalene or anthracene, and most preferably a group in which one or more hydrogen atoms have been removed from naphthalene.

Examples of the substituent which may be contained in Ra⁰⁰⁸ include the same one as the substituent which may be contained in Ra⁰⁰⁵.

In a case where Ra⁰⁰⁸ in General Formula (a0-r2-04) is a naphthyl group, the position at which the tertiary carbon atom in General Formula (a1-r2-4) is bonded is any of the 1-position and the 2-position of the naphthyl group.

In a case where Ra⁰⁰⁸ in Formula (a0-r2-04) is an anthryl group, the position at which the tertiary carbon atom in Formula (a0-r2-04) is bonded is any of the 1-position, the 2-position, and 9-position of the anthryl group.

Specific examples of the group represented by General Formula (a0-r2-01) are shown below.

Specific examples of the group represented by General Formula (a0-r2-02) are shown below.

Specific examples of the group represented by General Formula (a0-r2-03) are shown below.

Specific examples of the group represented by General Formula (a0-r2-04) are shown below.

In General Formula (a0-1), the acid dissociable group as Rx⁰¹ is preferably a tertiary alkyl ester-type acid dissociable group, and more preferably an acid dissociable group represented by any one of General Formula (a0-r2-01) to (a0-r2-03).

In General Formula (a0-1), q represents an integer in a range of 0 to 3. A case where q is 0 gives a benzene structure, a case where q is 1 gives a naphthalene structure, a case where q is 2 gives an anthracene structure, and a case where q is 3 gives a tetracene structure.

In General Formula (a0-1), n represents an integer of 1 or more, preferably an integer in a range of 1 to 5, more preferably an integer in a range of 1 to 3, and still more preferably an integer of 1 or 2.

In General Formula (a0-1), n≤q×2+4 is satisfied.

For example, in a case where q is 1, which gives a naphthalene structure, all hydrogen atoms in the naphthalene except for hydrogen atoms substituted with a polymerizable group-containing group (W⁰¹) and -Ya⁰¹-(C═O)—O-Rx⁰¹ group may be substituted with a hydroxy group. Further, in the naphthalene, the substitution positions of the polymerizable group-containing group (W⁰¹), -Ya⁰¹-(C═O)—O-Rx⁰¹ group, and the hydroxy group are not particularly limited.

Among the above, the constitutional unit (a01) is preferably a constitutional unit represented by General Formula (a0-1-1).

[In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya⁰⁰¹ represents a single bond or a divalent linking group. Ya⁰¹ represents a single bond or a divalent linking group. Rax⁰¹ represents the acid dissociable group represented by General Formula (a0-r-1) or (a0-r-2) described above, q represents an integer in a range of 0 to 3. n represents an integer of 1 or more. However, n≤q×2+4 is satisfied.]

In General Formula (a0-1-1), the alkyl group having 1 to 5 carbon atoms as R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. The halogenated alkyl group having 1 to 5 carbon atoms is a group obtained by substituting part or all hydrogen atoms in the alkyl group having 1 to 5 carbon atoms with a halogen atom. The halogen atom is particularly preferably a fluorine atom.

R is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and most preferably a hydrogen atom or a methyl group in terms of industrial availability.

In General Formula (a0-1-1), Ya⁰⁰¹ represents a single bond or a divalent linking group.

The divalent linking group as Ya⁰⁰¹ is not particularly limited. However, suitable examples thereof include a divalent hydrocarbon group which may have a substituent and a divalent linking group having a hetero atom, each of which is the same as the divalent hydrocarbon group as W⁰¹ and the divalent linking group containing a hetero atom.

Among the above, Ya⁰⁰¹ is preferably an ester bond [—C(═O)—O— or —O—C(═O)—], an ether bond (—O—), a linear or branched alkylene group, an aromatic hydrocarbon group, or a combination thereof, or a single bond. Among the above, Ya⁰⁰¹ is more preferably an ester bond [—C(═O)—O— or —O—C(═O)—], a combination of an ester bond [—C(═O)—O— or —O—C(═O)—] with a linear alkylene group or a single bond, and still more preferably an ester bond [—C(═O)—O— or —O—C(═O)—] or a single bond.

In General Formula (a0-1-1), Ya⁰¹ is the same as Ya⁰¹ in General Formula (a0-1).

In General Formula (a0-1-1), Rax⁰¹ represents the acid dissociable group represented by General Formula (a0-r-1) or (a0-r-2) described above.

In General Formula (a0-1-1), Rax⁰¹ is preferably, among the above, an acid dissociable group represented by any one of General Formula (a0-r2-01) or (a0-r2-03).

In General Formula (a0-1-1), q and n are the same as q and n in General Formula (a0-1).

Specific examples of the constitutional unit (a01) are shown below. In each of the formulae shown below, R^(α) represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

The constitutional unit (a01) in the resist composition according to the present embodiment is, among the above, preferably a constitutional unit represented by any of General Formula (a01-1a-1) to (a01-1a-46), more preferably a constitutional unit represented by any of General Formulae (a01-1a-1) to (a01-1a-40), and still more preferably a constitutional unit represented by any one of General Formulae (a01-1a-2), (a01-1a-4), (a01-1a-8), (a01-1a-25), (a01-1a-28), (a01-1a-31), (a01-1a-34), (a01-1a-37), (a01-1a-39), and (a01-1a-40).

The constitutional unit (a01) contained in the component (A1) may be one kind or may be two or more kinds.

The proportion of the constitutional unit (a01) in the component (A1) is preferably 50% by mole or more and may be 100% by mole with respect to the total (100% by mole) of all constitutional units constituting the component (A1). Among the above, the proportion of the constitutional unit (a01) in the component (A1) is more preferably in a range of 60% to 90% by mole and still more preferably in a range of 60% to 80% by mole.

In a case where the proportion of the constitutional unit (a01) is set within the above preferred range, sensitivity can be further improved without reducing resolution.

In addition, since the solubility of the developing solution can be suitably ensured, the fine resolution can be further improved.

<<Other Constitutional Units>>

The component (A1) may have other constitutional units as necessary in addition to the constitutional unit (a01).

Examples of the other constitutional units include a constitutional unit (a1) containing an acid decomposable group having a polarity which is increased under action of acid (provided that a constitutional unit corresponding to the constitutional unit (a01) is excluded); a constitutional unit (a10) represented by General Formula (a10-1) described later; a constitutional unit (a8) derived from a compound represented by General Formula (a8-1) described later; a constitutional unit (a2) containing a lactone-containing cyclic group, a —SO₂—-containing cyclic group, or a carbonate-containing cyclic group (provided that a constitutional unit corresponding to the constitutional unit (a01) or the constitutional unit (a1) is excluded); a constitutional unit (a3) containing a polar group-containing aliphatic hydrocarbon group (provided that a constitutional unit corresponding to the constitutional unit (a01), the constitutional unit (a1), the constitutional unit (a2), or the constitutional unit (a8) is excluded); a constitutional unit (a4) containing an acid non-dissociable aliphatic cyclic group; and a constitutional unit (st) derived from styrene or a styrene derivative.

In Regard to Constitutional Unit (a1):

The component (A1) may further have a constitutional unit (a1) in addition to the constitutional unit (a01).

The constitutional unit (a1) is a constitutional unit (provided that a constitutional unit corresponding to the constitutional unit (a01) is excluded) containing an acid decomposable group having a polarity which is increased under action of acid.

Examples of the acid dissociable group are the same as those which have been proposed so far as acid dissociable groups for the base resin for a chemically amplified resist composition.

Specific examples of the acid dissociable group of the base resin proposed for a chemically amplified resist composition include the “acetal-type acid dissociable group” and the “tertiary alkyl ester-type acid dissociable group” described above, and a “tertiary alkyloxycarbonyl acid dissociable group” described below.

Tertiary Alkyloxycarbonyl Acid Dissociable Group:

Examples of the acid dissociable group for protecting a hydroxyl group include an acid dissociable group (hereinafter, for convenience, also referred to as a “tertiary alkyloxycarbonyl acid dissociable group”) represented by General Formula (a1-r-3) shown below.

[In the formula, Ra′⁷ to Ra′⁹ each represent an alkyl group.]

In General Formula (a1-r-3), Ra′⁷ to Ra′⁹ are each preferably an alkyl group having 1 to 5 carbon atoms and more preferably an alkyl group having 1 to 3 carbon atoms.

Further, the total number of carbon atoms in each of the alkyl groups is preferably in a range of 3 to 7, more preferably in a range of 3 to 5, and most preferably 3 or 4.

Examples of the constitutional unit (a1) include a constitutional unit derived from acrylic acid ester in which the hydrogen atom bonded to the carbon atom at the ex-position may be substituted with a substituent; a constitutional unit derived from acrylamide; a constitutional unit in which at least part of hydrogen atoms in a hydroxyl group of a constitutional unit derived from hydroxystyrene or a hydroxystyrene derivative are protected by a substituent including an acid decomposable group; and a constitutional unit in which at least part of hydrogen atoms in —C(═O)—OH of a constitutional unit derived from vinylbenzoic acid or a vinylbenzoic acid derivative are protected by the substituent including an acid decomposable group.

Among the above, the constitutional unit (a1) is preferably a constitutional unit derived from acrylic acid ester in which the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent.

Preferred specific examples of such a constitutional unit (a1) include constitutional units represented by General Formula (a1-1) or (a1-2).

[In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Va¹ represents a divalent hydrocarbon group which may have an ether bond. n_(a1) represents an integer in a range of 0 to 2. Ra¹ is the acid dissociable group represented by General Formula (a0-r-1) or (a0-r-2) described above. Wa¹ represents an (n_(a2)+1)-valent hydrocarbon group, n_(a2) represents an integer in a range of 1 to 3, and Ra² represents the acid dissociable group represented by General Formula (a0-r-1) or (a1-r-3) described above.]

In General Formula (a1-1), the alkyl group having 1 to 5 carbon atoms as R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. The halogenated alkyl group having 1 to 5 carbon atoms is a group obtained by substituting part or all hydrogen atoms in the alkyl group having 1 to 5 carbon atoms with a halogen atom. The halogen atom is particularly preferably a fluorine atom.

R is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and most preferably a hydrogen atom or a methyl group in terms of industrial availability.

In General Formula (a1-1), the divalent hydrocarbon group as Va¹ may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

The aliphatic hydrocarbon group as the divalent hydrocarbon group represented by Va¹ may be saturated or unsaturated. In general, it is preferable that the aliphatic hydrocarbon group is saturated.

Specific examples of the aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, and an aliphatic hydrocarbon group containing a ring in the structure thereof.

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

The linear aliphatic hydrocarbon group is preferably a linear alkylene group, and specific examples thereof include a methylene group [—CH₂—], an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group has preferably 2 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms.

The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof include alkylalkylene groups, for example, alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

Examples of the aliphatic hydrocarbon group containing a ring in the structure thereof include an alicyclic hydrocarbon group (a group obtained by removing two hydrogen atoms from an aliphatic hydrocarbon ring), a group obtained by bonding the alicyclic hydrocarbon group to the terminal of a linear or branched aliphatic hydrocarbon group, and a group obtained by interposing the alicyclic hydrocarbon group is in a linear or branched aliphatic hydrocarbon group. Examples of the linear or branched aliphatic hydrocarbon group include the same one as the above-described linear aliphatic hydrocarbon group or the above-described branched aliphatic hydrocarbon group.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms and more preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be monocyclic or polycyclic. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a polycycloalkane, and the polycycloalkane is preferably a group having 7 to 12 carbon atoms. Specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

The aromatic hydrocarbon group as the divalent hydrocarbon group represented by Va¹ is a hydrocarbon group having an aromatic ring.

The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30 carbon atoms, still more preferably 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbon atoms. Here, the number of carbon atoms in a substituent is not included in the number of carbon atoms.

Specific examples of the aromatic ring contained in the aromatic hydrocarbon group include aromatic hydrocarbon rings such as benzene, biphenyl, fluorene, naphthalene, anthracene, and phenanthrene; and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting the above-described aromatic hydrocarbon rings with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group include a group in which two hydrogen atoms have been removed from the above-described aromatic hydrocarbon ring (an arylene group); and a group in which one hydrogen atom of a group (an aryl group) formed by removing one hydrogen atom from the aromatic hydrocarbon ring has been substituted with an alkylene group (for example, a group in which one or more hydrogen atoms have been removed from an aryl group in arylalkyl groups such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group). The alkylene group (an alkyl chain in the arylalkyl group) preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably 1 carbon atom.

In General Formula (a1-1), Ra¹ is an acid dissociable group represented by General Formula (a0-r-1) or (a0-r-2).

In General Formula (a1-2), the (n_(a2)+1)-valent hydrocarbon group as Wa¹ may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The aliphatic hydrocarbon group indicates a hydrocarbon group that has no aromaticity and may be saturated or unsaturated. In general, it is preferable that the aliphatic hydrocarbon group is saturated. Examples of the aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, an aliphatic hydrocarbon group containing a ring in the structure thereof, and a combination of the linear or branched aliphatic hydrocarbon group and the aliphatic hydrocarbon group containing a ring in the structure thereof.

The valency of (n_(a2)+1) is preferably divalent, trivalent, or tetravalent, and more preferably divalent or trivalent.

In General Formula (a1-2), Ra² is an acid dissociable group represented by General Formula (a0-r-1) or (a1-r-3).

Specific examples of the constitutional unit represented by General Formula (a1-1) are shown below. In each of the formulae shown below, R^(α) represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

The constitutional unit (a1) contained in the component (A1) may be one kind or may be two or more kinds.

The constitutional unit (a1) is more preferably a constitutional unit represented by General Formula (a1-1) since lithography characteristics (sensitivity, shape, and the like) in lithography depending on an electron beam or EUV can be more easily increased.

The proportion of the constitutional unit (a1) in the component (A1) is preferably in a range of 1% to 50% by mole, more preferably in a range of 5% to 40% by mole, and still more preferably in a range of 10% to 30% by mole, with respect to the total (100% by mole) of all constitutional units constituting the component (A1).

In a case where the proportion of the constitutional unit (a1) is equal to or larger than the lower limit value of the preferred range described above, lithography characteristics such as sensitivity, resolution, and roughness amelioration are improved. On the other hand, in a case where it is equal to or smaller than the upper limit value of the above preferred range, balance with other constitutional units can be obtained, and various lithography characteristics are improved.

In Regard to Constitutional Unit (a10):

The component (A1) may further have a constitutional unit (a10) represented by General Formula (a10-1).

[In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya^(x1) represents a single bond or a divalent linking group. Wa^(x1) represents an aromatic hydrocarbon group which may have a substituent, n_(ax1) represents an integer of 1 or more.]

In General Formula (a10-1), R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms.

The alkyl group having 1 to 5 carbon atoms as R is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group.

The halogenated alkyl group having 1 to 5 carbon atoms as R is a group obtained by substituting part or all hydrogen atoms of an above-described alkyl group having 1 to 5 carbon atoms with a halogen atom. The halogen atom is particularly preferably a fluorine atom.

R is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and in terms of industrial availability, R is more preferably a hydrogen atom, a methyl group, or trifluoromethyl group, still more preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group.

In General Formula (a10-1), Ya^(x1) represents a single bond or a divalent linking group.

In the chemical formulae described above, the divalent linking group as Ya^(x1) is not particularly limited, and suitable examples thereof include a divalent hydrocarbon group which may have a substituent and a divalent linking group having hetero atoms.

Divalent Hydrocarbon Group which May have Substituent:

In a case where Ya^(x1) represents a divalent hydrocarbon group which may have a substituent, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

Aliphatic Hydrocarbon Group as Ya^(x1)

The aliphatic hydrocarbon group indicates a hydrocarbon group that has no aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated. In general, it is preferable that the aliphatic hydrocarbon group is saturated.

Examples of the aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, and an aliphatic hydrocarbon group containing a ring in the structure thereof.

Linear or Branched Aliphatic Hydrocarbon Group

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

The linear aliphatic hydrocarbon group is preferably a linear alkylene group, and specific examples thereof include a methylene group [—CH₂—], an ethylene group [-(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group has preferably 2 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms.

The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof include alkylalkylene groups, for example, alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

The linear or branched aliphatic hydrocarbon group may have or may not have a substituent. Examples of the substituent include a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, which has been substituted with a fluorine atom, and a carbonyl group.

Aliphatic Hydrocarbon Group Containing Ring in Structure Thereof

Examples of the aliphatic hydrocarbon group containing a ring in the structure thereof include a cyclic aliphatic hydrocarbon group which may have a substituent containing a hetero atom in the ring structure thereof (a group obtained by removing two hydrogen atoms from an aliphatic hydrocarbon ring), a group obtained by bonding the cyclic aliphatic hydrocarbon group to the terminal of a linear or branched aliphatic hydrocarbon group, and a group obtained by interposing the cyclic aliphatic hydrocarbon group in a linear or branched aliphatic hydrocarbon group. Examples of the linear or branched aliphatic hydrocarbon group include the same ones as those described above.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms and more preferably 3 to 12 carbon atoms.

The cyclic aliphatic hydrocarbon group may be a polycyclic group or a monocyclic group. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a polycycloalkane, and the polycycloalkane is preferably a group having 7 to 12 carbon atoms. Specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

The cyclic aliphatic hydrocarbon group may have or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.

The alkoxy group as the substituent is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and still more preferably a methoxy group or an ethoxy group.

The halogen atom as the substituent is preferably a fluorine atom.

Examples of the halogenated alkyl group as the substituent include groups obtained by substituting part or all hydrogen atoms in the above-described alkyl groups with the above-described halogen atoms.

In the cyclic aliphatic hydrocarbon group, part of carbon atoms constituting the ring structure thereof may be substituted with a substituent containing a hetero atom.

The substituent containing a hetero atom is preferably —O—, —C(═O)—O—, —S—, —S(═O)₂—, or —S(═O)₂—O—.

Aromatic Hydrocarbon Group as Ya^(x1)

The aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.

The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having (4n+2) π electrons, and may be monocyclic or polycyclic. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Here, the number of carbon atoms in a substituent is not included in the number of carbon atoms.

Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting the above-described aromatic hydrocarbon ring with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocyclic ring include a pyridine ring and a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group (an arylene group or a heteroarylene group) obtained by removing two hydrogen atoms from the above-described aromatic hydrocarbon ring or the above-described aromatic heterocyclic ring; a group obtained by removing two hydrogen atoms from an aromatic compound having two or more aromatic rings (such as biphenyl or fluorene); and a group (for example, a group obtained by further removing one hydrogen atom from an aryl group in arylalkyl groups such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group) obtained by substituting one hydrogen atom of a group (an aryl group or a heteroaryl group) obtained by removing one hydrogen atom from the above aromatic hydrocarbon ring or the above aromatic heterocyclic ring, with an alkylene group. The alkylene group bonded to the aryl group or the heteroaryl group preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably 1 carbon atom.

In the aromatic hydrocarbon group, a hydrogen atom contained in the aromatic hydrocarbon group may be substituted with a substituent. For example, the hydrogen atom bonded to the aromatic ring in the aromatic hydrocarbon group may be substituted with a substituent. Examples of substituents include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.

Examples of the alkoxy group, the halogen atom, and the halogenated alkyl group, as the substituent, include those exemplified as the substituent that is substituted for a hydrogen atom contained in the cyclic aliphatic hydrocarbon group.

Divalent Linking Group Containing Hetero Atom:

In a case where Ya^(x1) represents a divalent linking group containing a hetero atom, preferred examples of the linking group include —O—, —C(═O)—O—, —O—C(═O)—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (H may be substituted with a substituent such as an alkyl group, an acyl group, or the like), —S—, —S(═O)₂—, —S(═O)₂—O—, and a group represented by General Formula —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—, —[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²— or —Y²¹—S(═O)₂—O—Y²²— [in the formulae, Y²¹ and Y²² each independently represent a divalent hydrocarbon group which may have a substituent, O represents an oxygen atom, and m″ represents an integer in a range of 0 to 3].

In a case where the divalent linking group containing a hetero atom is —C(═O)—NH—, —C(═O)—NH—C(═O)—, —NH—, or —NH—C(═NH)—, H may be substituted with a substituent such as an alkyl group, an acyl group, or the like. The substituent (an alkyl group, an acyl group, or the like) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 5 carbon atoms.

In General Formula —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—, —[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²—, or —Y²¹—S(═O)₂—O—Y²²—, Y²¹ and Y²² each independently represent a divalent hydrocarbon group which may have a substituent. Examples of the divalent hydrocarbon group include the same one as the divalent hydrocarbon groups which may have a substituent, mentioned in the explanation of the above-described divalent linking group as Ya^(x1).

Y²¹ is preferably a linear aliphatic hydrocarbon group, more preferably a linear alkylene group, still more preferably a linear alkylene group having 1 to 5 carbon atoms, and particularly preferably a methylene group or an ethylene group.

Y²² is preferably a linear or branched aliphatic hydrocarbon group and more preferably a methylene group, an ethylene group, or an alkylmethylene group. The alkyl group in the alkylmethylene group is preferably a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group.

In the group represented by General Formula —[Y²¹—C(═O)—O]_(m″)—Y²²—, m″ represents an integer in a range of 0 to 3, preferably an integer in a range of 0 to 2, more preferably 0 or 1, and particularly preferably 1. In other words, it is particularly preferable that the group represented by General Formula —[Y²¹—C(═O)—O]_(m″)—Y²²— represents a group represented by General Formula —Y²¹—C(═O)—O—Y²²—. Among these, a group represented by Formula —(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ represents an integer in a range of 1 to 10, preferably an integer in a range of 1 to 8, more preferably an integer in a range of 1 to 5, still more preferably 1 or 2, and most preferably 1. b′ represents an integer in a range of 1 to 10, preferably an integer in a range of 1 to 8, more preferably an integer in a range of 1 to 5, still more preferably 1 or 2, and most preferably 1.

Among the above, Ya^(x1) is preferably a single bond, an ester bond [—C(═O)—O—, —O—C(═O)—], an ether bond (—O—), a linear or branched alkylene group, or a combination thereof, and more preferably a single bond or an ester bond [—C(═O)—O—, —O—C(═O)—].

In General Formula (a10-1), Wa^(x1) represents an aromatic hydrocarbon group which may have a substituent.

Examples of the aromatic hydrocarbon group as Wa^(x1) include a group in which (n_(ax1)+1) hydrogen atoms have been removed from an aromatic ring which may have a substituent. Here, the aromatic ring is not particularly limited as long as it is a cyclic conjugated system having (4n+2) π electrons, and may be monocyclic or polycyclic. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and aromatic heterocyclic rings obtained by substituting part of carbon atoms constituting the above-described aromatic hydrocarbon ring with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocyclic ring include a pyridine ring and a thiophene ring.

Examples of the aromatic hydrocarbon group as Wa^(x1) also include a group in which (n_(ax1)+1) hydrogen atoms have been removed from an aromatic compound including an aromatic ring (for example, biphenyl and fluorene) which may have two or more substituents.

Among the above, Wa^(x1) is preferably a group in which (n_(ax1)+1) hydrogen atoms have been removed from benzene, naphthalene, anthracene, or biphenyl, more preferably a group in which (n_(ax1)+1) hydrogen atoms have been removed from benzene or naphthalene, and still more preferably a group in which (n_(ax1)+1) hydrogen atoms have been removed from benzene.

The aromatic hydrocarbon group as Wa^(x1) may or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, and a halogenated alkyl group. Examples of the alkyl group, the alkoxy group, the halogen atom, and the halogenated alkyl group, as the substituent, include the same ones as those described as the above-described substituent of the cyclic aliphatic hydrocarbon group as Ya^(x1). The substituent is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, more preferably a linear or branched alkyl group having 1 to 3 carbon atoms, still more preferably an ethyl group or a methyl group, and particularly preferably a methyl group. The aromatic hydrocarbon group as Wa^(x1) preferably has no substituent.

In General Formula (a10-1), n_(ax1) represents an integer of 1 or more, preferably an integer in a range of 1 to 10, more preferably an integer in a range of 1 to 5, still more preferably 1, 2, or 3, and particularly preferably 1 or 2.

Specific examples of the constitutional unit (a10) represented by General Formula (a10-1) are shown below.

In each of the formulae shown below, R^(α) represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

The constitutional unit (a10) contained in the component (A1) may be one kind or may be two or more kinds.

In a case where the component (A1) contains the constitutional unit (a10), the proportion of the constitutional unit (a 10) in the component (A1) is preferably in a range of 1% to 50% by mole and more preferably in a range of 10% to 40% by mole with respect to the total (100% by mole) of all constitutional units constituting the component (A1).

In a case where the proportion of the constitutional unit (a10) is equal to or larger than the lower limit value, the sensitivity can be more easily increased. On the other hand, in a case where it is equal to or smaller than the upper limit value, the balance with other constitutional units is easily obtained.

In regard to constitutional unit (a8):

The constitutional unit (a8) is a constitutional unit derived from a compound represented by General Formula (a8-1).

[In the formula, W² represents a polymerizable group-containing group. Ya^(x2) represents a single bond or an (n_(ax2)+1)-valent linking group. Ya^(x2) and W² may form a condensed ring. R¹ represents a fluorinated alkyl group having 1 to 12 carbon atoms. R² represents an organic group having 1 to 12 carbon atoms, which may have a fluorine atom, or a hydrogen atom. n_(ax2) represents an integer in a range of 1 to 3.]

In General Formula (a8-1), the polymerizable group-containing group as W² is the same as the polymerizable group-containing group as W⁰¹ in General Formula (a01-1).

In General Formula (a8-1), Ya^(x2) represents a single bond or an (n_(ax2)+1)-valent, that is, a divalent, trivalent, or tetravalent linking group.

Examples of the divalent linking group as Ya^(x2) include the same ones as those described as the divalent linking group as Ya^(x0) of W⁰¹ in General Formula (a01-1). Examples of the trivalent linking group as Ya^(x2) include a group in which one hydrogen atom has been removed from the above-described divalent linking group and a group in which the divalent linking group has been bonded to another divalent linking group. Examples of the tetravalent linking group include a group in which two hydrogen atoms are removed from the divalent linking group.

Ya^(x2) and W² may form a condensed ring.

In a case where Ya^(x2) and W² form a condensed ring, examples of the ring structure of the condensed ring include a condensed ring of an alicyclic hydrocarbon and an aromatic hydrocarbon. The condensed ring formed by Ya^(x2) and W² may have a hetero atom.

The alicyclic hydrocarbon moiety in the condensed ring formed by Ya^(x2) and W² may be a monocyclic ring or a polycyclic ring.

Examples of the condensed ring formed by Ya^(x2) and W² include a condensed ring formed by a polymerizable group of the W² moiety and by Ya^(x2) and a condensed ring formed by a group other than the polymerizable group of the W² moiety and by Ya^(x2). Specific examples thereof include a bicyclic condensed ring of a cycloalkene and an aromatic ring, a tricyclic condensed ring of a cycloalkene and two aromatic rings, and a bicyclic condensed ring of a cycloalkane having a polymerizable group as a substituent and an aromatic ring, and a tricyclic condensed ring of a cycloalkane having a polymerizable group as a substituent and an aromatic ring.

The condensed ring formed by Ya^(x2) and W² may have a substituent. Examples of this substituent include a methyl group, an ethyl group, propyl group, a hydroxy group, a hydroxyalkyl group, a carboxy group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, and the like), an alkoxy group (a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and the like), an acyl group, an alkyloxycarbonyl group, and an alkylcarbonyloxy group.

Specific examples of the condensed ring formed by Ya^(x2) and W² are shown below. W^(α) represents a polymerizable group.

In General Formula (a8-1), R¹ represents a fluorinated alkyl group having 1 to 12 carbon atoms.

The fluorinated alkyl group having 1 to 12 carbon atoms is a group in which part or all hydrogen atoms in the alkyl group having 1 to 12 carbon atoms have been substituted with a fluorine atom. The alkyl group may be linear or branched.

Specific examples of the linear fluorinated alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, and an undecyl group, a group obtained by substituting part or all hydrogen atoms of a dodecyl group substituted with a fluorine atom. Specific examples of the branched fluorinated alkyl group having 1 to 12 carbon atoms include a 1-methylethyl group, a 1,1-dimethylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a group in which part or all hydrogen atoms of a 4-methylpentyl group are substituted with a fluorine atom.

Among the above, the fluorinated alkyl group having 1 to 12 carbon atoms of R¹ is preferably a fluorinated alkyl group having 1 to 5 carbon atoms and specifically preferably a trifluoromethyl group.

In General Formula (a8-1), R² represents an organic group having 1 to 12 carbon atoms, which may have a fluorine atom, or a hydrogen atom.

Examples of the organic group having 1 to 12 carbon atoms as R², which may have a fluorine atom, include a monovalent hydrocarbon group having 1 to 12 carbon atoms, which may have a fluorine atom.

Examples of the hydrocarbon group include a linear or branched alkyl group and a cyclic hydrocarbon group.

Specific examples of the linear alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group.

Specific examples of the branched alkyl group include a 1-methylethyl group, a 1,1-dimethylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentyl group.

In a case where R² represents a cyclic hydrocarbon group, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group and may be a polycyclic group or a monocyclic group.

The aliphatic hydrocarbon group which is a monocyclic group is preferably a group obtained by removing one hydrogen atom from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane.

The aliphatic hydrocarbon group which is a polycyclic group is preferably a group obtained by removing one hydrogen atom from a polycycloalkane. The polycycloalkane preferably has 7 to 12 carbon atoms, and specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

In a case where the cyclic hydrocarbon group as R² is an aromatic hydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring. Specific examples of the aromatic hydrocarbon group include a group in which one hydrogen atom has been removed from an aromatic hydrocarbon ring such as benzene, naphthalene, anthracene, phenanthrene, biphenyl, and fluorene.

The organic group having 1 to 12 carbon atoms as R² may have a substituent other than the fluorine atom. Examples of the substituent include a hydroxy group, a carboxy group, a halogen atom (a chlorine atom, a bromine atom, and the like), an alkoxy group (a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and the like), and an alkyloxycarbonyl group.

R² is preferably a fluorinated alkyl group having 1 to 12 carbon atoms, more preferably a fluorinated alkyl group having 1 to 5 carbon atoms, and still more preferably a trifluoromethyl group.

In General Formula (a8-1), n_(ax2) represents an integer in a range of 1 to 3, preferably 1 or 2, and more preferably 1.

The constitutional unit (a8) is preferably a constitutional unit (a81) derived from a compound represented by General Formula (a8-1-1).

[In General Formula (a8-1-1), W² represents a polymerizable group-containing group. Wa^(x2) represents an (n_(ax2)+1)-valent cyclic group. W² and Wa^(x2) may form a condensed ring. R¹ represents a fluorinated alkyl group having 1 to 12 carbon atoms. R² represents an organic group having 1 to 12 carbon atoms, which may have a fluorine atom, or a hydrogen atom. n_(ax2) represents an integer in a range of 1 to 3.]

In General Formula (a8-1-1), W², R¹, R², and n_(ax2) are each the same as W², R¹, R², and n_(ax2) in General Formula (a8-1).

In General Formula (a8-1-1), Wa^(x2) is a (n_(ax2)+1)-valent cyclic group.

Examples of the cyclic group as Wa^(x2) include an aliphatic cyclic group and an aromatic cyclic group, and the cyclic group may be a monocyclic ring or a polycyclic ring.

The aliphatic cyclic group which is a monocyclic group is preferably a group in which one hydrogen atom has been removed from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane.

The aliphatic cyclic group which is a polycyclic group is preferably a group in which one hydrogen atom has been removed from a polycycloalkane. The polycycloalkane preferably has 7 to 12 carbon atoms, and specific examples thereof include a group in which one or more hydrogen atoms have been removed from a polycycloalkane such as decalin, perhydroazulene, or perhydroanthracene.

The aromatic cyclic group is a hydrocarbon group having at least one aromatic ring. The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having (4n+2) π electrons. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting the above-described aromatic hydrocarbon ring with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocyclic ring include a pyridine ring and a thiophene ring. Specific examples of the aromatic hydrocarbon group include a group obtained by removing one hydrogen atom from the above-described aromatic hydrocarbon ring or aromatic heterocyclic ring (an aryl group or a heteroaryl group); a group obtained by removing one hydrogen atom from an aromatic compound having two or more aromatic rings (biphenyl, fluorene or the like); and a group obtained by substituting one hydrogen atom of the above-described aromatic hydrocarbon ring or aromatic heterocyclic ring with an alkylene group (an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group). The alkylene group bonded to the aromatic hydrocarbon ring or aromatic heterocyclic ring preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably 1 carbon atom.

Examples of the substituent which may be contained in the cyclic group as Wa^(x2) include a carboxy group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, and the like), an alkoxy group (a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and the like), and an alkyloxycarbonyl group.

W² and Wa^(x2) may form a condensed ring, which is the same condensed ring as that described in the condensed ring formed by Ya^(x2) and W² in General Formula (a8-1).

Specific examples of the constitutional unit (a8) are shown below.

In the formulae shown below, R^(α) represents a hydrogen atom, a methyl group, or a trifluoromethyl group.

Among the above examples, the constitutional unit (a8) is preferably a constitutional unit represented by Chemical Formula (a8-1-01).

The constitutional unit (a8) contained in the component (A1) may be one kind or may be two or more kinds.

In a case where the component (A1) has the constitutional unit (a8), the proportion of the constitutional unit (a8) is preferably in a range of 1% to 40% by mole, more preferably in a range of 1% to 30% by mole, and still more preferably in a range of 5% to 15% by mole, with respect to the total (100% by mole) of all constitutional units constituting the component (A1).

In a case where the proportion of the constitutional unit (a8) is equal to or larger than the lower limit value of the preferred range, the compatibility with the developing solution and the rinse liquid can be enhanced. On the other hand, in a case where the proportion is equal to or smaller than the upper limit value of the preferred range, balance with other constitutional units can be obtained, and various lithography characteristics are improved.

In Regard to Constitutional Unit (a2):

The component (A1) may further have a constitutional unit (a2) (provided that a constitutional unit corresponding to the constitutional unit (a01) or the constitutional unit (a1) is excluded) containing a lactone-containing cyclic group, a —SO₂—-containing cyclic group, or a carbonate-containing cyclic group.

In a case where the component (A1) is used for forming a resist film, the lactone-containing cyclic group, the —SO₂—-containing cyclic group, or the carbonate-containing cyclic group in the constitutional unit (a2) is effective for improving the adhesiveness of the resist film to the substrate. Further, due to having the constitutional unit (a2), lithography characteristics can be improved, for example, by the effects obtained by appropriately adjusting the acid diffusion length, increasing the adhesiveness of the resist film to the substrate, and appropriately adjusting the solubility during development.

The “lactone-containing cyclic group” indicates a cyclic group that contains a ring (lactone ring) containing a —O—C(═O)— in the ring skeleton. In a case where the lactone ring is counted as the first ring and the group contains only the lactone ring, the group is referred to as a monocyclic group. Further, in a case where the group has other ring structures, the group is referred to as a polycyclic group regardless of the structures. The lactone-containing cyclic group may be a monocyclic group or a polycyclic group.

The lactone-containing cyclic group for the constitutional unit (a2) is not particularly limited, and any lactone-containing cyclic group may be used. Specific examples thereof include groups each represented by General Formulae (a2-r-1) to (a2-r-7) shown below.

[In the formulae, each Ra′²¹ independently represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, —COOR″, —OC(═O)R″, a hydroxyalkyl group, or a cyano group; R″ represents a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a —SO₂—-containing cyclic group; A″ represents an oxygen atom, a sulfur atom, or an alkylene group having 1 to 5 carbon atoms, which may contain an oxygen atom (—O—) or a sulfur atom (—S—); and n′ represents an integer in a range of 0 to 2, and m′ is 0 or 1.]

In General Formulae (a2-r-1) to (a2-r-7), the alkyl group as Ra′²¹ is preferably an alkyl group having 1 to 6 carbon atoms. The alkyl group is preferably a linear alkyl group or a branched alkyl group. Specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and a hexyl group. Among these, a methyl group or ethyl group is preferable, and a methyl group is particularly preferable.

The alkoxy group as Ra′²¹ is preferably an alkoxy group having 1 to 6 carbon atoms. Further, the alkoxy group is preferably a linear or branched alkoxy group. Specific examples of the alkoxy groups include a group formed by linking the above-described alkyl group mentioned as the alkyl group represented by Ra′²¹ to an oxygen atom (—O—).

The halogen atom as Ra′²¹ is preferably a fluorine atom.

Examples of the halogenated alkyl group as Ra′²¹ include a group obtained by substituting part or all hydrogen atoms in the above-described alkyl group as Ra′²¹ with the above-described halogen atoms. The halogenated alkyl group is preferably a fluorinated alkyl group and particularly preferably a perfluoroalkyl group.

In —COOR″ and —OC(═O)R″ as Ra′²¹, R″ represents a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a —SO₂—-containing cyclic group.

The alkyl group as R″ may be linear, branched, or cyclic, and preferably has 1 to carbon atoms.

In a case where R″ represents a linear or branched alkyl group, it is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and particularly preferably a methyl group or an ethyl group.

In a case where R″ represents a cyclic alkyl group, the cyclic alkyl group preferably has 3 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and particularly preferably 5 to 10 carbon atoms. Specific examples thereof include a group obtained by removing one or more hydrogen atoms from a monocycloalkane, which may be or may not be substituted with a fluorine atom or a fluorinated alkyl group; and a group obtained by removing one or more hydrogen atoms from a polycycloalkane such as bicycloalkane, tricycloalkane, or tetracycloalkane. More specific examples thereof include a group obtained by removing one or more hydrogen atoms from a monocycloalkane such as cyclopentane or cyclohexane; and a group obtained by removing one or more hydrogen atoms from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane.

Examples of the lactone-containing cyclic group as R″ include the same ones as the groups each represented by any one of General Formulae (a2-r-1) to (a2-r-7).

The carbonate-containing cyclic group as R″ has the same definition as that for the carbonate-containing cyclic group described below. Specific examples of the carbonate-containing cyclic group include groups each represented by any one of General Formulae (ax3-r-1) to (ax3-r-3).

The —SO₂—-containing cyclic group as R″ has the same definition as that for the —SO₂—-containing cyclic group described below. Specific examples thereof include groups each represented by any one of General Formulae (a5-r-1) to (a5-r-4).

The hydroxyalkyl group as Ra′²¹ preferably has 1 to 6 carbon atoms, and specific examples thereof include a group obtained by substituting at least one hydrogen atom in the alkyl group as Ra′²¹ with a hydroxyl group.

In General Formulae (a2-r-2), (a2-r-3) and (a2-r-5), as the alkylene group having 1 to 5 carbon atoms as A″, a linear or branched alkylene group is preferable, and examples thereof include a methylene group, an ethylene group, an n-propylene group, and an isopropylene group. Specific examples of the alkylene groups that contain an oxygen atom or a sulfur atom include a group obtained by interposing —O— or —S— in the terminal of the alkylene group or between the carbon atoms of the alkylene group, and examples thereof include —O—CH₂—, —CH₂—O—CH₂—, —S—CH₂—, and —CH₂—S—CH₂—. A″ is preferably an alkylene group having 1 to 5 carbon atoms or —O—, more preferably an alkylene group having 1 to 5 carbon atoms, and most preferably a methylene group.

Specific examples of the groups each represented by any one of General Formulae (a2-r-1) to (a2-r-7) are shown below.

The “—SO₂—-containing cyclic group” indicates a cyclic group having a ring containing —SO₂— in the ring skeleton thereof. Specifically, it is a cyclic group in which the sulfur atom (S) in —SO₂— forms a part of the ring skeleton of the cyclic group. In a case where the ring containing —SO₂— in the ring skeleton thereof is counted as the first ring and the group contains only the ring, the group is referred to as a monocyclic group.

In a case where the group further has other ring structures, the group is referred to as a polycyclic group regardless of the ring structures. The —SO₂—-containing cyclic group may be a monocyclic group or a polycyclic group.

The —SO₂—-containing cyclic group is particularly preferably a cyclic group containing —O—SO₂— in the ring skeleton thereof, in other words, a cyclic group containing a sultone ring in which —O—S— in the —O—SO₂— group forms a part of the ring skeleton thereof.

More specific examples of the —SO₂—-containing cyclic group include groups each represented by any one of General Formulae (a5-r-1) to (a5-r-4) shown below.

[In the formulae, each Ra′⁵¹ independently represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, —COOR″, —OC(═O)R″, a hydroxyalkyl group, or a cyano group; R″ represents a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a —SO₂—-containing cyclic group; A″ represents an oxygen atom, a sulfur atom, or an alkylene group having 1 to 5 carbon atoms, which may contain an oxygen atom or a sulfur atom; and n′ represents an integer in a range of 0 to 2.]

In General Formulae (a5-r-1) and (a5-r-2), A″ has the same definition as that for A″ in General Formulae (a2-r-2), (a2-r-3) and (a2-r-5). Respective examples of the alkyl group, the alkoxy group, the halogen atom, the halogenated alkyl group, —COOR″, —OC(═O)R″, and the hydroxyalkyl group as Ra′⁵¹ include the same ones as those mentioned in the explanation of Ra′²¹ in General Formulae (a2-r-1) to (a2-r-7).

Specific examples of the groups each represented by any one of General Formulae (a5-r-1) to (a5-r-4) are shown below. In the formulae shown below, “Ac” represents an acetyl group.

The “carbonate-containing cyclic group” indicates a cyclic group having a ring (a carbonate ring) containing —O—C(═O)—O— in the ring skeleton thereof. In a case where the carbonate ring is counted as the first ring and the group contains only the carbonate ring, the group is referred to as a monocyclic group.

Further, in a case where the group has other ring structures, the group is referred to as a polycyclic group regardless of the structures. The carbonate-containing cyclic group may be a monocyclic group or a polycyclic group.

The carbonate ring-containing cyclic group is not particularly limited, and any carbonate ring-containing cyclic group may be used. Specific examples thereof include groups each represented by any one of General Formulae (ax3-r-1) to (ax3-r-3) shown below.

[In the formulae, Ra′^(x31)s independently represent a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, —COOR″, —OC(═O)R″, a hydroxyalkyl group, or a cyano group; R″ represents a hydrogen atom, an alkyl group, a lactone-containing cyclic group, a carbonate-containing cyclic group, or a —SO₂—-containing cyclic group; A″ represents an oxygen atom, a sulfur atom, or an alkylene group having 1 to 5 carbon atoms, which may contain an oxygen atom or a sulfur atom; and p′ represents an integer in a range of 0 to 3, and q′ is 0 or 1.]

In General Formulae (ax3-r-2) and (ax3-r-3), A″ has the same definition as that for A″ in General Formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Respective examples of the alkyl group, the alkoxy group, the halogen atom, the halogenated alkyl group, —COOR″, —OC(═O)R″, and the hydroxyalkyl group as Ra′³¹ include the same ones as those mentioned in the explanation of Ra′²¹ in General Formulae (a2-r-1) to (a2-r-7).

Specific examples of the groups each represented by any one of General Formulae (ax3-r-1) to (ax3-r-3) are shown below.

Among them, the constitutional unit (a2) is preferably a constitutional unit derived from acrylic acid ester in which the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent.

Such a constitutional unit (a2) is preferably a constitutional unit represented by General Formula (a2-1).

[In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms. Ya²¹ represents a single bond or a divalent linking group. La²¹ represents —O—, —COO—, —CON(R′)—, —OCO—, —CONHCO— or —CONHCS—, and R′ represents a hydrogen atom or a methyl group. However, in a case where La²¹ represents —O—, Ya²¹ does not represent —CO—. Ra²¹ represents a lactone-containing cyclic group, a carbonate-containing cyclic group, or a —SO₂—-containing cyclic group.]

In General Formula (a2-1), R has the same definition as described above. R is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms, and particularly preferably a hydrogen atom or a methyl group in terms of industrial availability.

In General Formula (a2-1), the divalent linking group as Ya²¹ is not particularly limited, and suitable examples thereof include a divalent hydrocarbon group which may have a substituent and a divalent linking group having a hetero atom.

Divalent Hydrocarbon Group which May have Substituent:

In a case where Ya²¹ represents a divalent hydrocarbon group which may have a substituent, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

Aliphatic Hydrocarbon Group as Ya²¹

The aliphatic hydrocarbon group indicates a hydrocarbon group that has no aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated. In general, it is preferable that the aliphatic hydrocarbon group is saturated.

Examples of the aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, and an aliphatic hydrocarbon group containing a ring in the structure thereof.

Linear or Branched Aliphatic Hydrocarbon Group

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

The linear aliphatic hydrocarbon group is preferably a linear alkylene group, and specific examples thereof include a methylene group [—CH₂—], an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group has preferably 2 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms.

The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof include alkylalkylene groups, for example, alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

The linear or branched aliphatic hydrocarbon group may have or may not have a substituent. Examples of the substituent include a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, which has been substituted with a fluorine atom, and a carbonyl group.

Aliphatic Hydrocarbon Group Containing Ring in Structure Thereof

Examples of the aliphatic hydrocarbon group containing a ring in the structure thereof include a cyclic aliphatic hydrocarbon group which may have a substituent containing a hetero atom in the ring structure thereof (a group obtained by removing two hydrogen atoms from an aliphatic hydrocarbon ring), a group obtained by bonding the cyclic aliphatic hydrocarbon group to the terminal of a linear or branched aliphatic hydrocarbon group, and a group obtained by interposing the cyclic aliphatic hydrocarbon group in a linear or branched aliphatic hydrocarbon group. Examples of the linear or branched aliphatic hydrocarbon group include the same ones as those described above.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms and more preferably 3 to 12 carbon atoms.

The cyclic aliphatic hydrocarbon group may be a polycyclic group or a monocyclic group. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a polycycloalkane, and the polycycloalkane is preferably a group having 7 to 12 carbon atoms. Specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

The cyclic aliphatic hydrocarbon group may have or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.

The alkoxy group as the substituent is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and still more preferably a methoxy group or an ethoxy group.

The halogen atom as the substituent is preferably a fluorine atom.

Examples of the halogenated alkyl group as the substituent include groups obtained by substituting part or all hydrogen atoms in the above-described alkyl groups with the above-described halogen atoms.

In the cyclic aliphatic hydrocarbon group, part of carbon atoms constituting the ring structure thereof may be substituted with a substituent containing a hetero atom. The substituent containing a hetero atom is preferably —O—, —C(═O)—O—, —S—, —S(═O)₂—, or —S(═O)₂—O—.

Aromatic Hydrocarbon Group as Ya²¹

The aromatic hydrocarbon group is a hydrocarbon group having at least one aromatic ring.

The aromatic ring is not particularly limited as long as it is a cyclic conjugated system having (4n+2) π electrons, and may be monocyclic or polycyclic. The aromatic ring preferably has 5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Here, the number of carbon atoms in a substituent is not included in the number of carbon atoms.

Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and phenanthrene; and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting the above-described aromatic hydrocarbon ring with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the aromatic heterocyclic ring include a pyridine ring and a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group (an arylene group or a heteroarylene group) obtained by removing two hydrogen atoms from the above-described aromatic hydrocarbon ring or the above-described aromatic heterocyclic ring; a group obtained by removing two hydrogen atoms from an aromatic compound having two or more aromatic rings (such as biphenyl or fluorene); and a group (for example, a group obtained by further removing one hydrogen atom from an aryl group in arylalkyl groups such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethyl group) obtained by substituting one hydrogen atom of a group (an aryl group or a heteroaryl group) obtained by removing one hydrogen atom from the above aromatic hydrocarbon ring or the above aromatic heterocyclic ring, with an alkylene group. The alkylene group bonded to the aryl group or the heteroaryl group preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably 1 carbon atom.

In the aromatic hydrocarbon group, a hydrogen atom contained in the aromatic hydrocarbon group may be substituted with a substituent. For example, the hydrogen atom bonded to the aromatic ring in the aromatic hydrocarbon group may be substituted with a substituent. Examples of substituents include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.

Examples of the alkoxy group, the halogen atom, and the halogenated alkyl group, as the substituent, include those exemplified as the substituent that is substituted for a hydrogen atom contained in the cyclic aliphatic hydrocarbon group.

Divalent Linking Group Containing Hetero Atom:

In a case where Ya²¹ represents a divalent linking group containing a hetero atom, preferred examples of the linking group include —O—, —C(═O)—O—, —O—C(═O)—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (H may be substituted with a substituent such as an alkyl group, an acyl group, or the like), —S—, —S(═O)₂—, —S(═O)₂—O—, and a group represented by General Formula —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—, —[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²— or —Y²¹—S(═O)₂—O—Y²²— [in the formulae, Y²¹ and Y²² each independently represent a divalent hydrocarbon group which may have a substituent, O represents an oxygen atom, and m″ represents an integer in a range of 0 to 3].

In a case where the divalent linking group containing a hetero atom is —C(═O)—NH—, —C(═O)—NH—C(═O)—, —NH—, or —NH—C(═NH)—, H may be substituted with a substituent such as an alkyl group, an acyl group, or the like. The substituent (an alkyl group, an acyl group, or the like) preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 5 carbon atoms.

In General Formula —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—, —[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²—, or —Y²¹—S(═O)₂—O—Y²²—, Y²¹ and Y²² each independently represent a divalent hydrocarbon group which may have a substituent. Examples of the divalent hydrocarbon group include the same one as the divalent hydrocarbon groups which may have a substituent, mentioned in the explanation of the above-described divalent linking group as Ya²¹.

Y²¹ is preferably a linear aliphatic hydrocarbon group, more preferably a linear alkylene group, still more preferably a linear alkylene group having 1 to 5 carbon atoms, and particularly preferably a methylene group or an ethylene group.

Y²² is preferably a linear or branched aliphatic hydrocarbon group and more preferably a methylene group, an ethylene group, or an alkylmethylene group. The alkyl group in the alkylmethylene group is preferably a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group.

In the group represented by General Formula —[Y²¹—C(═O)—O]_(m″)—Y²²—, m″ represents an integer in a range of 0 to 3, preferably an integer in a range of 0 to 2, more preferably 0 or 1, and particularly preferably 1. In other words, it is particularly preferable that the group represented by General Formula —[Y²¹—C(═O)—O]_(m″)—Y²²— represents a group represented by General Formula —Y²¹—C(═O)—O—Y²²—. Among these, a group represented by Formula —(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ represents an integer in a range of 1 to 10, preferably an integer in a range of 1 to 8, more preferably an integer in a range of 1 to 5, still more preferably 1 or 2, and most preferably 1. b′ represents an integer in a range of 1 to 10, preferably an integer in a range of 1 to 8, more preferably an integer in a range of 1 to 5, still more preferably 1 or 2, and most preferably 1.

Among the above, Ya²¹ is preferably a single bond, an ester bond [—C(═O)—O—], an ether bond (—O—), a linear or branched alkylene group, or a combination thereof.

In General Formula (a2-1), Ra²¹ represents a lactone-containing cyclic group, a —SO₂—-containing cyclic group, or a carbonate-containing cyclic group.

Suitable examples of each of the lactone-containing cyclic group, the —SO₂—-containing cyclic group, and the carbonate-containing cyclic group as Ra²¹ include groups each represented by any one of General Formulae (a2-r-1) to (a2-r-7), groups each represented by any one of General Formulae (a5-r-1) to (a5-r-4), and groups each represented by any one of General Formulae (ax3-r-1) to (ax3-r-3) described above.

Among them, a lactone-containing cyclic group or a —SO₂—-containing cyclic group is preferable, and any one of groups each represented General Formula (a2-r-1), (a2-r-2), (a2-r-6), or (a5-r-1) is preferable. Specifically, any one of groups each represented Chemical Formulae (r-1c-1-1) to (r-1c-1-7), (r-1c-2-1) to (r-1c-2-18), (r-1c-6-1), (r-s1-1-1), and (r-s1-1-18) is more preferable, and a group represented by Chemical Formula (r-1c-1-1) is preferable.

The constitutional unit (a2) contained in the component (A1) may be one kind or may be two or more kinds.

In a case where the component (A1) has the constitutional unit (a2), the proportion of the constitutional unit (a2) is preferably in a range of 5% to 40% by mole and more preferably in a range of 5% to 30% by mole, with respect to the total (100% by mole) of all constitutional units constituting the component (A1).

In a case where the proportion of the constitutional unit (a2) is equal to or larger than the lower limit value of the preferred range, the effect obtained by allowing the component (A1) to contain the constitutional unit (a2) can be sufficiently achieved by the effect described above. In a case where it is equal to or smaller than the upper limit value of the preferred range, the balance with other constitutional units can be obtained, and various lithography characteristics are improved.

In Regard to Constitutional Unit (a3):

The component (A1) may further have a constitutional unit (a3) (provided that a constitutional unit corresponding to the constitutional unit (a01), the constitutional unit (a1), the constitutional unit (a2), or the constitutional unit (a8) is excluded) containing a polar group-containing aliphatic hydrocarbon group. In a case where the component (A1) has the constitutional unit (a3), the hydrophilicity of the component (A1) is increased, which contributes to an improvement in resolution. Further, acid diffusion length can be appropriately adjusted.

Examples of the polar group include a hydroxyl group, a cyano group, and a carboxy group, and a hydroxyl group is particularly preferable.

Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group (preferably an alkylene group) having 1 to 10 carbon atoms, and a cyclic aliphatic hydrocarbon group (a cyclic group). The cyclic group may be a monocyclic group or a polycyclic group. For example, these cyclic groups can be suitably selected from a large number of groups that have been proposed in resins for a resist composition for an ArF excimer laser.

In a case where the cyclic group is a monocyclic group, the monocyclic group preferably has 3 to 10 carbon atoms. Among the above, a constitutional unit derived from an acrylic acid ester containing an aliphatic monocyclic group, which contains a hydroxyl group, a cyano group, or a carboxy group, is more preferable. Examples of the monocyclic group include a group obtained by removing two or more hydrogen atoms from a monocycloalkane. Specific examples of the monocyclic group include a group obtained by removing two or more hydrogen atoms from a monocycloalkane such as cyclopentane, cyclohexane, or cyclooctane. Among these monocyclic groups, a group obtained by removing two or more hydrogen atoms from cyclopentane or a group obtained by removing two or more hydrogen atoms from cyclohexane are industrially preferable.

In a case where the cyclic group is a polycyclic group, the polycyclic group preferably has 7 to 30 carbon atoms. Among the above, a constitutional unit derived from an acrylic acid ester containing an aliphatic polycyclic group, which contains a hydroxyl group, a cyano group, or a carboxy group, is more preferable. Examples of the polycyclic group include groups obtained by removing two or more hydrogen atoms from a bicycloalkane, tricycloalkane, tetracycloalkane, or the like. Specific examples thereof include a group obtained by removing two or more hydrogen atoms from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Among these polycyclic groups, a group obtained by removing two or more hydrogen atoms from adamantane, a group obtained by removing two or more hydrogen atoms from norbornane, or a group obtained by removing two or more hydrogen atoms from tetracyclododecane are industrially preferable.

The constitutional unit (a3) is not particularly limited, and any constitutional unit may be used as long as the constitutional unit contains a polar group-containing aliphatic hydrocarbon group.

The constitutional unit (a3) is preferably a constitutional unit derived from an acrylic acid ester in which the hydrogen atom bonded to the carbon atom at the ex-position may be substituted with a substituent, where the constitutional unit contains a polar group-containing aliphatic hydrocarbon group.

In a case where the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms, the constitutional unit (a3) is preferably a constitutional unit derived from a hydroxy ethyl ester of acrylic acid.

Examples of the preferred constitutional unit (a3) include a constitutional unit represented by General Formula (a3-1) and a constitutional unit represented by General Formula (a3-2).

[In the formula, R is the same as above, j represents an integer in a range of 1 to 3, and k represents an integer in a range of 1 to 3.]

In General Formula (a3-1), j is preferably 1 or 2 and more preferably 1. In a case where j represents 2, it is preferable that the hydroxyl groups is bonded to the 3- and 5-positions of the adamantyl group. In a case where j represents 1, it is preferable that the hydroxyl group is bonded to the 3-position of the adamantyl group.

It is preferable that j represents 1, and it is particularly preferable that the hydroxyl group be bonded to the 3-position of the adamantyl group.

In General Formula (a3-2), k is preferably 1. The cyano group is preferably bonded to the 5- or 6-position of the norbornyl group.

The constitutional unit (a3) contained in the component (A1) may be one kind or may be two or more kinds.

In a case where the component (A1) has the constitutional unit (a3), the proportion of the constitutional unit (a3) is preferably in a range of 1% to 30% by mole, more preferably in a range of 2% to 25% by mole, and still more preferably in a range of 5% to 20% by mole, with respect to the total (100% by mole) of all constitutional units constituting the component (A1).

In a case where the proportion of the constitutional unit (a3) is equal to or larger than the lower limit value of the preferred range, the effect obtained by allowing the component (A1) to contain the constitutional unit (a3) can be sufficiently achieved by the effect described above. In a case where it is equal to or smaller than the upper limit value of the preferred range, the balance with other constitutional units can be obtained, and various lithography characteristics are improved.

In Regard to Constitutional Unit (a4):

The component (A1) may further have a constitutional unit (a4) containing an acid non-dissociable aliphatic cyclic group.

In a case where the component (A1) has the constitutional unit (a4), the dry etching resistance of the formed resist pattern is improved. Further, the hydrophobicity of the component (A1) increases. The improvement in hydrophobicity contributes to the improvement in resolution, a resist pattern shape, and the like, particularly in the case of a solvent developing process.

The “acid non-dissociable cyclic group” in the constitutional unit (a4) is a cyclic group that remains in the constitutional unit without being dissociated even in a case where an acid acts in a case where the acid is generated in the resist composition by exposure (for example, in a case where acid is generated from the constitutional unit that generates acid upon exposure, or the component (B)).

Examples of the constitutional unit (a4) preferably include a constitutional unit derived from an acrylic acid ester including an acid non-dissociable aliphatic cyclic group. As the cyclic group, many cyclic groups conventionally known as cyclic groups used as a resin component of a resist composition for ArF excimer laser, KrF excimer laser (preferably ArF excimer laser), or the like can be used.

The cyclic group is particularly preferably at least one selected from a tricyclodecyl group, an adamantyl group, a tetracyclododecyl group, an isobornyl group, and a norbornyl group, from the viewpoint of industrial availability. These polycyclic groups may have, as a substituent, a linear or branched alkyl group having 1 to 5 carbon atoms.

Specific examples of the constitutional unit (a4) include constitutional units each represented by General Formulae (a4-1) to (a4-7).

[In the formula, R^(α) is the same as above.]

The constitutional unit (a4) contained in the component (A1) may be one kind or may be two or more kinds.

In a case where the component (A1) has the constitutional unit (a4), the proportion of the constitutional unit (a4) is preferably in a range of 1% to 40% by mole and more preferably in a range of 1% to 20% by mole, with respect to the total (100% by mole) of all constitutional units constituting the component (A1).

In a case where the proportion of the constitutional unit (a4) is equal to or larger than the lower limit value of the preferred range, the effect obtained by allowing the constitutional unit (a4) to be contained can be sufficiently achieved. In a case it is equal to or smaller than the upper limit value of the preferred range, the balance with other constitutional units is easily obtained.

In Regard to Constitutional Unit (St):

The constitutional unit (st) is a constitutional unit derived from styrene or a styrene derivative. A “constitutional unit derived from styrene” means a constitutional unit that is formed by the cleavage of an ethylenic double bond of styrene. A “constitutional unit derived from a styrene derivative” means a constitutional unit (provided that a constitutional unit corresponding to the constitutional unit (a10) is excluded) formed by the cleavage of an ethylenic double bond of a styrene derivative.

The “styrene derivative” means a compound obtained by substituting at least part of hydrogen atoms of styrene with a substituent. Examples of the styrene derivative include a derivative obtained by substituting a hydrogen atom at the α-position of styrene with a substituent, a derivative obtained by substituting one or more hydrogen atoms of the benzene ring of styrene with a substituent, and a derivative obtained by substituting a hydrogen atom at the α-position of styrene and one or more hydrogen atoms of the benzene ring with a substituent.

Examples of the substituent that is substituted for the hydrogen atom at the α-position of styrene include an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms.

The alkyl group having 1 to 5 carbon atoms is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group.

The halogenated alkyl group having 1 to 5 carbon atoms is a group obtained by substituting part or all hydrogen atoms in the alkyl group having 1 to 5 carbon atoms with a halogen atom. The halogen atom is particularly preferably a fluorine atom.

The substituent that is substituted for the hydrogen atom at the α-position of styrene is preferably an alkyl group having 1 to 5 carbon atoms or a fluorinated alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms or a fluorinated alkyl group having 1 to 3 carbon atoms, and still more preferably a methyl group from the viewpoint of industrial availability.

Examples of the substituent that is substituted for the hydrogen atom of the benzene ring of styrene include an alkyl group, an alkoxy group, a halogen atom, and a halogenated alkyl group.

The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group.

The alkoxy group as the substituent is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and still more preferably a methoxy group or an ethoxy group.

The halogen atom as the substituent is preferably a fluorine atom.

Examples of the halogenated alkyl group as the substituent include groups obtained by substituting part or all hydrogen atoms in the above-described alkyl groups with the above-described halogen atoms.

The substituent that is substituted for the hydrogen atom of the benzene ring of styrene is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a methyl group or an ethyl group, and still more preferably a methyl group.

The constitutional unit (st) is preferably a constitutional unit derived from styrene or a constitutional unit derived from a styrene derivative obtained by substituting a hydrogen atom at the α-position of styrene with an alkyl group having 1 to 5 carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms, more preferably a constitutional unit derived from styrene, or a constitutional unit derived from a styrene derivative obtained by substituting a hydrogen atom at the α-position of styrene with a methyl group, and still more preferably a constitutional unit derived from styrene.

The constitutional unit (st) contained in the component (A1) may be one kind or may be two or more kinds.

In a case where the component (A1) has the constitutional unit (st), the proportion of the constitutional unit (st) is preferably in a range of 1% to 30% by mole and more preferably in a range of 1% to 20% by mole with respect to the total (100% by mole) of all constitutional units constituting the component (A1).

The component (A1) contained in the resist composition may be used alone or in a combination of two or more kinds thereof.

In the resist composition according to the present embodiment, the component (A1) is a resin component that contains the constitutional unit (a01).

Suitable examples of such a component (A1) include a polymeric compound consisting of only a repeating structure of the constitutional unit (a01); a polymeric compound having a repeating structure of the constitutional unit (a01) and the constitutional unit (a10); a polymeric compound having a repeating structure of the constitutional unit (a01), the constitutional unit (a10), and the constitutional unit (a2); a polymeric compound having a repeating structure of the constitutional unit (a01), the constitutional unit (a10), and the constitutional unit (a8); a polymeric compound having a repeating structure of the constitutional unit (a01), the constitutional unit (a2), and the constitutional unit (a3); and a polymeric compound having a repeating structure of the constitutional unit (a01) and the constitutional unit (a1). Among them, a polymeric compound having a repeating structure of the constitutional unit (a01) and the constitutional unit (a10) is preferable.

In the polymeric compound having a repeating structure of the constitutional unit (a01) and the constitutional unit (a10), the proportion of the constitutional unit (a01) in the polymeric compound is preferably in a range of 50% to 95% by mole, more preferably in a range of 60% to 80% by mole, and still more preferably in a range of 65% to 75% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In addition, the proportion of the constitutional unit (a10) in the polymeric compound is preferably in a range of 5% to 50% by mole, more preferably in a range of 20% to 40% by mole, still more preferably in a range of 25% to 35% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In the polymeric compound having a repeating structure of the constitutional unit (a01), the constitutional unit (a10), and the constitutional unit (a2), the proportion of the constitutional unit (a01) in the polymeric compounds is preferably in a range of 50% to 80% by mole, more preferably in a range of 60% to 80% by mole, and still more preferably in a range of 65% to 75% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In addition, the proportion of the constitutional unit (a10) in the polymeric compound is preferably in a range of 1% to 40% by mole, more preferably in a range of 10% to 30% by mole, still more preferably in a range of 15% to 25% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In addition, the proportion of the constitutional unit (a2) in the polymeric compound is preferably in a range of 1% to 30% by mole, more preferably in a range of 3% to 20% by mole, still more preferably in a range of 5% to 15% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In the polymeric compound having a repeating structure of the constitutional unit (a01), the constitutional unit (a10), and the constitutional unit (a8), the proportion of the constitutional unit (a01) in the polymeric compounds is preferably in a range of 50% to 80% by mole, more preferably in a range of 60% to 80% by mole, and still more preferably in a range of 65% to 75% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In addition, the proportion of the constitutional unit (a10) in the polymeric compound is preferably in a range of 1% to 40% by mole, more preferably in a range of 10% to 30% by mole, still more preferably in a range of 15% to 25% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In addition, the proportion of the constitutional unit (a8) in the polymeric compound is preferably in a range of 1% to 30% by mole, more preferably in a range of 3% to 20% by mole, still more preferably in a range of 5% to 15% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In the polymeric compound having a repeating structure of the constitutional unit (a01), the constitutional unit (a2), and the constitutional unit (a3), the proportion of the constitutional unit (a01) in the polymeric compounds is preferably in a range of 65% to 95% by mole, more preferably in a range of 70% to 90% by mole, and still more preferably in a range of 75% to 85% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In addition, the proportion of the constitutional unit (a2) in the polymeric compound is preferably in a range of 1% to 30% by mole, more preferably in a range of 3% to 20% by mole, still more preferably in a range of 5% to 15% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In addition, the proportion of the constitutional unit (a3) in the polymeric compound is preferably in a range of 1% to 30% by mole, more preferably in a range of 3% to 20% by mole, still more preferably in a range of 5% to 15% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In the polymeric compound having a repeating structure of the constitutional unit (a01) and the constitutional unit (a1), the proportion of the constitutional unit (a01) in the polymeric compound is preferably in a range of 50% to 95% by mole, more preferably in a range of 60% to 90% by mole, and still more preferably in a range of 75% to 85% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

In addition, the proportion of the constitutional unit (a1) in the polymeric compound is preferably in a range of 5% to 50% by mole, more preferably in a range of 10% to 40% by mole, still more preferably in a range of 15% to 25% by mole, with respect to the total (100% by mole) of all constitutional units constituting the polymeric compound.

The component (A1) can be produced by dissolving, in a polymerization solvent, each monomer from which the constitutional unit is derived, adding thereto a radical polymerization initiator such as azobisisobutyronitrile (AIBN) or dimethyl azobisisobutyrate (for example, V-601) to carry out polymerization.

Alternatively, the component (A1) can be produced by dissolving, in a polymerization solvent, a monomer from which the constitutional unit (a01) is derived and, as necessary, a monomer (for example, a compound in which a hydroxyl group of a monomer from which the constitutional unit (a10) is derived is protected) from which a constitutional unit other than the constitutional unit (a01) is derived, and adding thereto a radical polymerization initiator as described above to carry out polymerization and then carrying out a deprotection reaction.

Further, a —C(CF₃)₂—OH group may be introduced into the terminal of the component (A1) during the polymerization using a chain transfer agent such as HS—CH₂—CH₂—CH₂—C(CF₃)₂—OH in combination. As described above, a copolymer into which a hydroxyalkyl group, formed by substitution of part of hydrogen atoms in the alkyl group with fluorine atoms, has been introduced is effective for reducing development defects and reducing line edge roughness (LER: uneven irregularities of a line side wall).

The weight average molecular weight (Mw) (based on the polystyrene equivalent value determined by gel permeation chromatography (GPC)) of the component (A1), which is not particularly limited, is preferably in a range of 1,000 to 50,000, more preferably in a range of 2,000 to 30,000, and still more preferably in a range of 3,000 to 20,000.

In a case where Mw of the component (A1) is equal to or smaller than the upper limit value of this preferred range, a resist solvent solubility sufficient to be used as a resist is exhibited. On the other hand, in a case where it is equal to or larger than the lower limit value of this preferred range, dry etching resistance and the cross-sectional shape of the resist pattern become excellent.

Further, the dispersity (Mw/Mn) of the component (A1) is not particularly limited, but is preferably in a range of 1.0 to 4.0, more preferably in a range of 1.0 to 3.0, and particularly preferably in a range of 1.0 to 2.0. Mn represents the number average molecular weight.

In Regard to Component (A2)

In the resist composition according to the present embodiment, a base material component (hereinafter, referred to as a “component (A2)”) exhibiting changed solubility in a developing solution under action of acid, which does not correspond to the component (A1), may be used in combination as the component (A).

The component (A2) is not particularly limited and may be freely selected and used from a large number of conventionally known base material components for the chemically amplified resist composition.

As the component (A2), one kind of a polymeric compound or low molecular weight compound may be used alone, or a combination of two or more kinds thereof may be used.

The proportion of the component (A1) in the component (A) is preferably 25% by mass or more, more preferably 50% by mass or more, still more preferably 75% by mass or more, and may be 100% by mass with respect to the total mass of the component (A). In a case where the proportion is 25% by mass or more, a resist pattern having various excellent lithography characteristics such as high sensitivity, resolution, and roughness amelioration can be easily formed.

The content of the component (A) in the resist composition according to the present embodiment may be adjusted depending on the resist film thickness to be formed and the like.

<Acid Generator Component (B)>

The resist composition according to the present embodiment may further contain an acid generator component (B) that generates acid upon exposure in addition to the component (A). In the present embodiment, the component (B) contains a compound (B01) (hereinafter, also referred to as a “compound (B01)”) represented by General Formula (b0-1) or a compound (B02) (hereinafter, also referred to as a “compound (B02)”) represented by General Formula (b0-2).

[In General Formula (b0-1), R^(b1) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group. R^(b2) and R^(b3) each independently represent an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent. Two of R^(b1) to R^(b3) may be bonded to each other to form a ring together with a sulfur atom in the formula. X₀₁ ⁻ represents a counter anion.

In General Formula (b0-2), R^(b4) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group. R^(b5) represents an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent. X₀₂ ⁻ represents a counter anion.]

<<Compound (B01)>>

The compound (B01) is a compound represented by General Formula (b0-1).

[In General Formula (b0-1), R^(b1) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group. R^(b2) and R^(b3) each independently represent an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent. Two of R^(b1) to R^(b3) may be bonded to each other to form a ring together with a sulfur atom in the formula. X₀f represents a counter anion.]

In Regard to Cation Moiety

In General Formula (b0-1), R^(b1) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group.

The aryl group as R^(b1) preferably has 5 to 30 carbon atoms, more preferably 5 to carbon atoms, particularly preferably 6 to 15 carbon atoms, and most preferably 6 to carbon atoms. Here, the number of carbon atoms in a substituent is not included in the number of carbon atoms.

Specifically, the aryl group as R^(b1) is preferably a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, or a biphenyl group, more preferably a phenyl group or a naphthyl group, and still more preferably a phenyl group.

Specific examples of the fluorinated alkyl group contained in the aryl group as R^(b1) include a group obtained by substituting part or all hydrogen atoms of an alkyl group having 1 to 12 carbon atoms with a fluorine atom. The alkyl group may be linear or branched.

Specific examples of the linear fluorinated alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, and an undecyl group, a group obtained by substituting part or all hydrogen atoms of a dodecyl group substituted with a fluorine atom. Specific examples of the branched fluorinated alkyl group having 1 to 12 carbon atoms include a 1-methylethyl group, a 1,1-dimethylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a group in which part or all hydrogen atoms of a 4-methylpentyl group are substituted with a fluorine atom.

The fluorinated alkyl group contained in the aryl group as R^(b1) is, among the above, preferably a group obtained by substituting part or all hydrogen atoms of an alkyl group having 1 to 5 carbon atoms with a fluorine atom, more preferably a group obtained by substituting part or all hydrogen atoms of an alkyl group having 1 to 3 carbon atoms with a fluorine atom, and still more preferably a trifluoromethyl group.

The aryl group as R^(b1) may have a substituent other than the fluorine atom and the fluorinated alkyl group. Examples of the substituent include an alkyl group, a halogen atom other than the fluorine atom, a halogenated alkyl group other than the fluorinated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, any one of groups each represented by General Formulae (ca-r-1) to (ca-r-7), and a monovalent group represented by —SO₂—R^(b0) (R^(b0) is a linear or branched alkyl group which may have a substituent, an alicyclic hydrocarbon group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent).

[In the formulae, each R′²⁰¹ independently represents a hydrogen atom, a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent.]

Cyclic Group which May have Substituent:

The cyclic group is preferably a cyclic hydrocarbon group, and the cyclic hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. The aliphatic hydrocarbon group indicates a hydrocarbon group that has no aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated. In general, it is preferable that the aliphatic hydrocarbon group is saturated.

The aromatic hydrocarbon group as R′²⁰¹ is a hydrocarbon group having an aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30 carbon atoms, still more preferably 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, and most preferably 6 to 10 carbon atoms. Here, the number of carbon atoms in a substituent is not included in the number of carbon atoms.

Specific examples of the aromatic ring contained in the aromatic hydrocarbon group as R′²⁰¹ include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting one of these aromatic rings with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group as R′²⁰¹ include a group (an aryl group such as a phenyl group or a naphthyl group) obtained by removing one hydrogen atom from the above-described aromatic ring and a group (an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, 1-naphthylethyl group, or a 2-naphthylethyl group) obtained by substituting one hydrogen atom in the aromatic ring with an alkylene group. The alkylene group (an alkyl chain in the arylalkyl group) preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably 1 carbon atom.

Examples of the cyclic aliphatic hydrocarbon group as R′²⁰¹ include aliphatic hydrocarbon groups containing a ring in the structure thereof.

Examples of the aliphatic hydrocarbon group containing a ring in the structure thereof include an alicyclic hydrocarbon group (a group obtained by removing one hydrogen atom from an aliphatic hydrocarbon ring), a group obtained by bonding the alicyclic hydrocarbon group to the terminal of a linear or branched aliphatic hydrocarbon group, and a group obtained by interposing the alicyclic hydrocarbon group is in a linear or branched aliphatic hydrocarbon group.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms and more preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be a polycyclic group or a monocyclic group. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a polycycloalkane, and the poly cycloalkane preferably has 7 to 30 carbon atoms. Among the above, the polycycloalkane is preferably a polycycloalkane having a bridged ring-based polycyclic skeleton, such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane; or a poly cycloalkane having a condensed ring-based polycyclic skeleton, such as a cyclic group having a steroid skeleton.

The linear or branched aliphatic hydrocarbon group which may be bonded to the alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and particularly preferably 1 to 3 carbon atoms.

The linear aliphatic hydrocarbon group is preferably a linear alkylene group, and specific examples thereof include a methylene group [—CH₂—], an ethylene group [-(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof include alkylalkylene groups, for example, alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

The cyclic hydrocarbon group as R′²⁰¹ may contain a hetero atom such as a heterocyclic ring. Specific examples thereof include lactone-containing cyclic groups each represented by any one of General Formulae (a2-r-1) to (a2-r-7), —SO₂—-containing cyclic groups each represented by any one of General Formulae (a5-r-1) to (a5-r-4), and other heterocyclic groups each represented by any one of Chemical Formulae (r-hr-1) to (r-hr-16).

Examples of the substituent of the cyclic group as R′²⁰¹ include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, and a nitro group.

Chain-Like Alkyl Group which May have Substituent:

The chain-like alkyl group as R′²⁰¹ may be linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to carbon atoms, and most preferably 1 to 10 carbon atoms.

The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and most preferably 3 to 10 carbon atoms. Specific examples thereof include a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentyl group.

Chain-Like Alkenyl Group which May have Substituent:

Such a chain-like alkenyl group as R′²⁰¹ may be linear or branched, preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, still more preferably 2 to 4 carbon atoms, and particularly preferably 3 carbon atoms. Examples of the linear alkenyl group include a vinyl group, a propenyl group (an allyl group), and a butynyl group. Examples of the branched alkenyl group include a 1-methylvinyl group, a 2-methylvinyl group, a 1-methylpropenyl group, and a 2-methylpropenyl group.

Among the above, the chain-like alkenyl group is preferably a linear alkenyl group, more preferably a vinyl group or a propenyl group, and particularly preferably a vinyl group.

Examples of the substituent in the chain-like alkyl group or alkenyl group as R′²⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, an amino group, a cyclic group as R′²⁰¹ or the like may be used.

In the monovalent group represented by —SO₂—R^(b0), R^(b0) represents a linear or branched alkyl group which may have a substituent, an alicyclic hydrocarbon group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.

Examples of the linear or branched alkyl group of R^(b0) include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group, and a methyl group or an ethyl group is preferable, and a methyl group is more preferable.

Examples of the substituent which may be contained in the linear or branched alkyl group of R^(b0) include a halogen atom, a halogenated alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxy group, a carbonyl group, and a carboxy group.

The alicyclic hydrocarbon group of R^(b0) preferably has 3 to 20 carbon atoms, more preferably 3 to 12 carbon atoms, and may be polycyclic or monocyclic. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclobutane, cyclopentane, and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a poly cycloalkane, where the poly cycloalkane is preferably a group having 7 to 12 carbon atoms. Specific examples thereof include adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.

Examples of the substituent which may be contained in the alicyclic hydrocarbon group of R^(b0) include the same group as Ra^(x5) described above.

Examples of the aromatic hydrocarbon group of R^(b0) include a group obtained by removing one hydrogen atom from an aromatic hydrocarbon ring such as benzene, biphenyl, fluorene, naphthalene, anthracene, or phenanthrene.

Examples of the substituent which may be contained in the aromatic hydrocarbon group of R^(b0) include the same group as Ra^(x5) described above.

In General Formula (b0-1), R^(b2) and R^(b3) each independently represent an aryl group which may have a substituent, an alkyl group which may have a substituent, or an alkenyl group which may have a substituent.

Examples of the aryl group as R^(b2) and R^(b3) include the same one as the aryl group as R^(b1). Specifically, the aryl group as R^(b2) and R^(b3) is, among them, preferably a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, or a biphenyl group, more preferably a phenyl group or a naphthyl group, and still more preferably a phenyl group.

The alkyl group as R^(b2) and R^(b3) is preferably a chain-like or cyclic alkyl group having 1 to 30 carbon atoms.

The alkenyl group as R^(b2) and R^(b3) is preferably an alkenyl group having 2 to 10 carbon atoms.

In General Formula (b0-1), examples of the substituent which may be contained in R^(b2) and R^(b3) include an alkyl group, a halogen atom, a halogenated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, and groups each represented by General Formulae (ca-r-1) to (ca-r-7).

In General Formula (b0-1), R^(b2) and R^(b3) are, among the above, preferably an aryl group which may have a substituent. In a case where the aryl group has a substituent, the substituent is preferably a fluorine atom, a fluorinated alkyl group, or a monovalent group represented by —SO₂—R^(b0), and more preferably a fluorine atom, a fluorinated alkyl group, or a methanesulfonyl group (a mesyl group). That is, in General Formula (b0-1), R^(b2) and R^(b3) are particularly preferably an aryl group having an unsubstituted aryl group, an aryl group having a fluorine atom, an aryl group having a fluorinated alkyl group, and an aryl group having a methanesulfonyl group (a mesyl group).

In General Formula (b0-1), two of R^(b1) to R^(b3) may be bonded to each other to form a ring together with a sulfur atom in the formula. In a case where two of R^(b1) to R^(b3) are bonded to each other to form a ring together with a sulfur atom in the formula, they may be bonded to each other via a hetero atom such as a sulfur atom, an oxygen atom, or a nitrogen atom, or a functional group such as —SO—, —SO₂—, —SO₃—, —C(═O)—, —COO—, —CONH— or —N(R_(N))— (here, R_(N) represents an alkyl group having 1 to 5 carbon atoms). Regarding the ring to be formed, a ring containing a sulfur atom in a formula in the ring skeleton thereof is preferably a 3-membered to 10-membered ring and particularly preferably a 5-membered to 7-membered ring containing a sulfur atom.

Specific examples of the ring to be formed include a thiophene ring, a thiazole ring, a benzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthene ring, a thianthrene ring, a phenoxathiin ring, a tetrahydrothiophenium ring, and a tetrahydrothiopyranium ring.

In a case where R^(b1) and R^(b2) or R^(b3) are bonded to each other to form a ring together with a sulfur atom in the formula, the ring structure is not limited as long as it has a fluorine atom or a fluorinated alkyl group, and the hydrogen atom of the structure (for example, the benzene ring structure) derived from an aryl group may not be substituted with a fluorine atom or a fluorinated alkyl group.

The cation moiety in the compound (B01) is preferably a cation represented by General Formula (ca-b01-1).

[In the formula, R^(b2) and R^(b3) each independently represent an aryl group which may have a substituent, an alkyl group which may have a substituent, or an alkenyl group which may have a substituent. R^(b2) and R^(b3) may be bonded to each other to form a ring together with a sulfur atom in the formula. X⁰¹¹ represents a fluorine atom or a fluorinated alkyl group. R⁰¹¹ represents a substituent, nb represents an integer of 1 or more, pb represents an integer of 0 or more, qb represents an integer in a range of 0 to 3. However, nb+pb≤qb×2+5 is satisfied.]

In General Formula (ca-b01-1), R^(b2) and R^(b3) are each the same as R^(b2) and R^(b3) in General Formula (b0-1) described above.

In General Formula (ca-b01-1), X⁰¹¹ represents a fluorine atom or a fluorinated alkyl group, and examples thereof include the same one as the fluorine atom or the fluorinated alkyl group contained in R^(b1) in General Formula (b0-1) described above.

In General Formula (ca-b01-1), R⁰¹¹ represents a substituent, and examples thereof include an alkyl group, a halogen atom other than the fluorine atom, a halogenated alkyl group other than the fluorinated alkyl group, a carbonyl group, a cyano group, an amino group, an aryl group, and groups each represented by General Formula (ca-r-1) to (ca-r-7) described above. Among them, a monovalent group represented by —SO₂—R^(b0) is preferable, and a methanesulfonyl group (a mesyl group) is more preferable.

In General Formula (ca-b01-1), nb represents an integer of 1 or more, preferably an integer in a range of 1 to 3, and more preferably 1 or 2.

In General Formula (ca-b01-1), pb represents an integer of 0 or more and preferably an integer in a range of 0 to 2.

In General Formula (ca-b01-1), qb represents an integer in a range of 0 to 3. A case where q is 0 gives a benzene structure, a case where q is 1 gives a naphthalene structure, a case where q is 2 gives an anthracene structure, and a case where q is 3 gives a tetracene structure.

Particularly preferable cations as the cation moiety in the compound (B01) are shown below.

Among the above, the cation moiety in the component (B01) is preferably a cation represented by any one of General Formulae (ca-b01-11) to (ca-b01-20).

In Regard to Anion Moiety

In General Formula (b0-1), X₀f represents a counter anion. An anion known as an anion moiety of an acid generator component for a resist composition can be appropriately used.

Examples of X₀f include an anion represented by General Formula (b0-1-an1), an anion represented by General Formula (b0-1-an2), or an anion represented by General Formula (b0-1-an3).

[In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represent a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent, R¹⁰⁴ and R¹⁰⁵ may be bonded to each other to form a ring structure. R¹⁰² represents a fluorinated alkyl group having 1 to 5 carbon atoms or a fluorine atom. Y¹⁰¹ represents a divalent linking group containing an oxygen atom or a single bond. V¹⁰¹ to V¹⁰³ each independently represents a single bond, an alkylene group, or a fluorinated alkylene group. L¹⁰¹ and L¹⁰² each independently represent a single bond or an oxygen atom. L¹⁰³ to L¹⁰⁵ each independently represents a single bond, —CO—, or —SO₂-.]

Anion Represented by General Formula (b0-1-An1)

In General Formula (b0-1-an1), R¹⁰¹ represents a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent.

Cyclic Group which May have Substituent:

The cyclic group is preferably a cyclic hydrocarbon group, and the cyclic hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. The aliphatic hydrocarbon group indicates a hydrocarbon group that has no aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated. In general, it is preferable that the aliphatic hydrocarbon group is saturated.

The aromatic hydrocarbon group as R¹⁰¹ is a hydrocarbon group having an aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30 carbon atoms, more preferably 5 to 30, still more preferably 5 to 20, and particularly preferably 6 to 18. Here, the number of carbon atoms in a substituent is not included in the number of carbon atoms.

Specific examples of the aromatic ring contained in the aromatic hydrocarbon group as R¹⁰¹ include benzene, fluorene, naphthalene, anthracene, phenanthrene, biphenyl, and an aromatic heterocyclic ring obtained by substituting part of carbon atoms constituting any one of these aromatic rings with a hetero atom. Examples of the hetero atom in the aromatic heterocyclic ring include an oxygen atom, a sulfur atom, and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group as R¹⁰¹ include a group (an aryl group: for example, a phenyl group or a naphthyl group) obtained by removing one hydrogen atom from the above aromatic ring; a group (for example, an arylalkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, 1-naphthylethyl group, or a 2-naphthylethyl group) obtained by substituting one hydrogen atom of the above aromatic ring with an alkylene group; and a group obtained by removing one hydrogen atom from a condensed ring in which the above aromatic ring is condensed with a crosslinked aliphatic ring such as bicycloheptane or bicyclooctane. The alkylene group (an alkyl chain in the arylalkyl group) preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms, and particularly preferably 1 carbon atom.

Examples of the cyclic aliphatic hydrocarbon group as R¹⁰¹ include aliphatic hydrocarbon groups containing a ring in the structure thereof.

Examples of the aliphatic hydrocarbon group containing a ring in the structure thereof include an alicyclic hydrocarbon group (a group obtained by removing one hydrogen atom from an aliphatic hydrocarbon ring), a group obtained by bonding the alicyclic hydrocarbon group to the terminal of a linear or branched aliphatic hydrocarbon group, and a group obtained by interposing the alicyclic hydrocarbon group is in a linear or branched aliphatic hydrocarbon group.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms and more preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be a polycyclic group or a monocyclic group. The monocyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a monocycloalkane. The monocycloalkane preferably has 3 to 6 carbon atoms, and specific examples thereof include cyclopentane and cyclohexane. The polycyclic alicyclic hydrocarbon group is preferably a group obtained by removing one or more hydrogen atoms from a polycycloalkane, and the poly cycloalkane preferably has 7 to 30 carbon atoms. Among the above, the polycycloalkane is preferably a polycycloalkane having a bridged ring-based polycyclic skeleton, such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane; or a polycycloalkane having a condensed ring-based polycyclic skeleton, such as a cyclic group having a steroid skeleton.

Among them, the cyclic aliphatic hydrocarbon group as R¹⁰¹ is preferably a group obtained by removing one or more hydrogen atoms from a monocycloalkane or a polycycloalkane, more preferably a group obtained by removing one hydrogen atom from a polycycloalkane, and particularly preferably an adamantyl group or a norbornyl group.

The linear aliphatic hydrocarbon group which may be bonded to the alicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms. The linear aliphatic hydrocarbon group is preferably a linear alkylene group, and specific examples thereof include a methylene group [—CH₂—], an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group which may be bonded to the alicyclic hydrocarbon group preferably has 2 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbon atoms, and most preferably 3 carbon atoms. The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof include alkylalkylene groups, for example, alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

The cyclic hydrocarbon group as R¹⁰¹ may be a condensed cyclic group containing a condensed ring in which an aliphatic hydrocarbon ring and an aromatic ring are condensed. Examples of the condensed ring include a condensed ring in which one or more aromatic rings are condensed with a polycycloalkane having a bridged ring-based polycyclic skeleton. Specific examples of the bridged ring-based poly cycloalkane include bicycloalkanes such as bicyclo[2.2.1]heptane (norbornane) and bicyclo[2.2.2]octane. The condensed cyclic group is preferably a group containing a condensed ring, in which two or three aromatic rings are condensed with a bicycloalkane, and more preferably a group containing a condensed ring, in which two or three aromatic rings are condensed with bicyclo[2.2.2]octane. Specific examples of the condensed cyclic group as R¹⁰¹ include those represented by General Formulae (r-br-1) to (r-br-2). In the formulae, * represents a bonding site at which Y¹⁰¹ in General Formula (b0-1-an1) is bonded.

The cyclic hydrocarbon group as R¹⁰¹ may contain a hetero atom such as a heterocyclic ring. Specific examples thereof include lactone-containing cyclic groups each represented by any one of General Formulae (a2-r-1) to (a2-r-7), —SO₂—-containing cyclic groups each represented by any one of General Formulae (a5-r-1) to (a5-r-4), and other heterocyclic groups each represented by any one of Chemical Formulae (r-hr-1) to (r-hr-16).

Examples of the substituent of the cyclic group as R¹⁰¹ include an alkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, and a nitro group.

The alkyl group as the substituent is preferably an alkyl group having 1 to 5 carbon atoms, and a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group is most preferable.

The alkoxy group as the substituent is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, or a tert-butoxy group, and most preferably a methoxy group or an ethoxy group.

The halogen atom as a substituent is preferably a bromine atom, an iodine atom, or a fluorine atom, and a bromine atom or an iodine atom is more preferable.

Examples of the halogenated alkyl group as a substituent include a group obtained by substituting part or all hydrogen atoms in an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, or a tert-butyl group, with a halogen atom.

The carbonyl group as the substituent is a group that substitutes a methylene group (—CH₂—) constituting the cyclic hydrocarbon group.

Among the above, the substituent in the cyclic group as R¹⁰¹ is preferably a hydroxyl group, an alkoxy group, a bromine atom or an iodine atom, and more preferably a hydroxyl group, a bromine atom, or an iodine atom.

Chain-Like Alkyl Group which May have Substituent:

The chain-like alkyl group as R¹⁰¹ may be linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to carbon atoms, and most preferably 1 to 10 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decanyl group, an undecyl group, a dodecyl group, a tridecyl group, an isotridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, an isohexadecyl group, a heptadecyl group, an octadecyl group, a nonadecil group, an icosyl group, a henicosyl group, and a docosyl group.

The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably 3 to 15, and most preferably 3 to 10. Specific examples thereof include a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentyl group.

Chain-Like Alkenyl Group which May have Substituent:

A chain-like alkenyl group as R¹⁰¹ may be linear or branched, and the chain-like alkenyl group preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, still more preferably 2 to 4 carbon atoms, and particularly preferably 3 carbon atoms. Examples of the linear alkenyl group include a vinyl group, a propenyl group (an allyl group), and a butynyl group. Examples of the branched alkenyl group include a 1-methylvinyl group, a 2-methylvinyl group, a 1-methylpropenyl group, and a 2-methylpropenyl group.

Among the above, the chain-like alkenyl group is preferably a linear alkenyl group, more preferably a vinyl group or a propenyl group, and particularly preferably a vinyl group.

Examples of the substituent in the chain-like alkyl group or alkenyl group as R¹⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carbonyl group, a nitro group, an amino group, a cyclic group as R¹⁰¹ or the like may be used.

Among the above, R¹⁰¹ is preferably a cyclic group which may have a substituent. In addition, from the viewpoint of reducing roughness, R¹⁰¹ is more preferably a polycyclic hydrocarbon group which may have a substituent, and still more preferably a bridged ring-based polycyclic hydrocarbon group which may have a substituent. The cyclic group (the polycyclic hydrocarbon group) may contain a hetero atom like the heterocyclic ring or the like. In addition, from the viewpoint of improving sensitivity, R¹⁰¹ is preferably a cyclic group having an iodine atom or a bromine atom, and more preferably an aromatic hydrocarbon group having an iodine atom or a bromine atom.

Examples of the polycyclic hydrocarbon group include a group obtained by removing one hydrogen atom from a polycycloalkane having a polycyclic skeleton and a group obtained by removing one hydrogen atom from a condensed ring in which an aromatic ring is condensed with a polycycloalkane having a polycyclic skeleton. Examples of the polycycloalkane include a polycycloalkane having a bridged ring-based polycyclic skeleton, such as adamantane, norbornane (bicycloheptane), or a bicyclooctane; and a polycycloalkane having a condensed ring-based polycyclic skeleton, such as a cyclic group having a steroid skeleton. Among them, a polycycloalkane having a bridged ring-based polycyclic skeleton is preferable. Preferred specific examples of the polycyclic aliphatic hydrocarbon group include an adamantyl group and a norbornyl group.

Examples of the group obtained by removing one hydrogen atom from a condensed ring in which an aromatic ring is condensed with a polycycloalkane having a polycyclic skeleton include a group obtained by removing one hydrogen atom from a condensed ring of the above polycycloalkane with a benzene ring.

The polycyclic hydrocarbon group having a heterocycle is preferably a bridged ring-based polycyclic hydrocarbon group having a heterocycle, and specific examples thereof include —SO₂—-containing bridged ring-based polycyclic groups each represented by General Formulae (a5-r-1) and (a5-r-1).

In General Formula (b0-1-an1), Y¹⁰¹ represents a single bond or a divalent linking group containing an oxygen atom.

In a case where Y¹⁰¹ represents a divalent linking group containing an oxygen atom, Y¹⁰¹ may contain an atom other than the oxygen atom. Examples of the atom other than the oxygen atom include a carbon atom, a hydrogen atom, a sulfur atom, and a nitrogen atom.

Examples of divalent linking groups containing an oxygen atom include non-hydrocarbon-based oxygen atom-containing linking groups such as an oxygen atom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonyl group (—O—C(═O)—), an amide bond (—C(═O)—NH—), a carbonyl group (—C(═O)—), or a carbonate bond (—O—C(═O)—O—); and combinations of the above-described non-hydrocarbon-based oxygen atom-containing linking groups with an alkylene group. Furthermore, a sulfonyl group (—SO₂—) may be linked to the combination. Examples of such a divalent linking group containing an oxygen atom include linking groups each represented by General Formulae (y-a1-1) to (y-a1-7) shown below.

[In the formulae, V′¹⁰¹ represents a single bond or an alkylene group having 1 to carbon atoms, and V′¹⁰² represents a divalent saturated hydrocarbon group having 1 to carbon atoms.]

The divalent saturated hydrocarbon group as V′¹⁰² is preferably an alkylene group having 1 to 30 carbon atoms, more preferably an alkylene group having 1 to 10 carbon atoms, and still more preferably an alkylene group having 1 to 5 carbon atoms.

The alkylene group as V′¹⁰¹ and V′¹⁰² may be a linear alkylene group or a branched alkylene group, and a linear alkylene group is preferable.

Specific examples of the alkylene group as V′¹⁰¹ and V′¹⁰² include a methylene group [—CH₂—]; an alkylmethylene group such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, or —C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂—]; an alkylethylene group such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, or —CH(CH₂CH₃)CH₂—; a trimethylene group (n-propylene group) [—CH₂CH₂CH₂—]; an alkyltrimethylene group such as —CH(CH₃)CH₂CH₂— or —CH₂CH(CH₃)CH₂—; a tetramethylene group [—CH₂CH₂CH₂CH₂—]; an alkyltetramethylene group such as —CH(CH₃)CH₂CH₂CH₂—, or —CH₂CH(CH₃)CH₂CH₂—; and a pentamethylene group [—CH₂CH₂CH₂CH₂CH₂—].

Further, part of methylene groups in the alkylene group as V′¹⁰¹ and V′¹⁰² may be substituted with a divalent aliphatic cyclic group having 5 to 10 carbon atoms. The aliphatic cyclic group is preferably a divalent group in which one hydrogen atom has been removed from the cyclic aliphatic hydrocarbon group (a monocyclic aliphatic hydrocarbon group or a polycyclic aliphatic hydrocarbon group) as Ra′³ in General Formula (a1-r-1), and a cyclohexylene group, a 1,5-adamantylene group, or a 2,6-adamantylene group is more preferable.

Among the above, Y¹⁰¹ is preferably a single bond or an ester bond (—C(═O)—O—), or an oxycarbonyl group (—O—C(═O)—).

In General Formula (b0-1-an1), V¹⁰¹ represents a single bond, an alkylene group, or a fluorinated alkylene group. The alkylene group and the fluorinated alkylene group as V¹⁰¹ preferably have 1 to 4 carbon atoms. Examples of the fluorinated alkylene group as V¹⁰¹ include a group obtained by substituting part or all hydrogen atoms in the alkylene group as V¹⁰¹ with a fluorine atom. Among these examples, as V¹⁰¹, a single bond or a fluorinated alkylene group having 1 to 3 carbon atoms is preferable.

In General Formula (b0-1-an1), R¹⁰² represents a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms. R¹⁰² is preferably a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms and more preferably a fluorine atom.

Anion Represented by General Formula (b0-1-An2)

In General Formula (b0-1-an2), R¹⁰⁴ and R¹⁰⁵ each independently represent a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent or a chain-like alkenyl group which may have a substituent, and examples thereof each include the same one as the R¹⁰¹ in General Formula (b0-1-an1). However, R¹⁰⁴ and R¹⁰⁵ may be bonded to each other to form a ring.

As R¹⁰⁴ and R¹⁰⁵, a chain-like alkyl group which may have a substituent is preferable, and a linear or branched alkyl group or a linear or branched fluorinated alkyl group is more preferable.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 7 carbon atoms, and still more preferably 1 to 3 carbon atoms. It is preferable that the number of carbon atoms in the chain-like alkyl group as R¹⁰⁴ and R¹⁰⁵ is small since the solubility in a resist solvent is also excellent in this range of the number of carbon atoms. In addition, in the chain alkyl group R¹⁰⁴ and R¹⁰⁵, the larger the number of hydrogen atoms substituted with a fluorine atom, the stronger the acid strength, which is preferable. The proportion of fluorine atoms in the chain-like alkyl group, that is, the fluorination ratio is preferably in a range of 70% to 100% and more preferably in a range of 90% to 100%, and it is most preferable that the chain-like alkyl group is a perfluoroalkyl group in which all hydrogen atoms is substituted with a fluorine atom.

in General Formula (b0-1-an2), V¹⁰² and V¹⁰³ each independently represent a single bond, an alkylene group, or a fluorinated alkylene group, and examples thereof each include the same one as V¹⁰¹ in General Formula (b0-1-an1).

In General Formula (b0-1-an2), L¹⁰¹ and L¹⁰² each independently represent a single bond or an oxygen atom.

Anion Represented by General Formula (b0-1-An3)

In Formula (b0-1-an3), R¹⁰⁶ to R¹⁰⁸ each independently represents a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent or a chain-like alkenyl group which may have a substituent, and examples thereof each include the same one as R¹⁰¹ in Formula (b0-1-an1).

In General Formula (b0-1-an3), L¹⁰³ to L¹⁰⁵ each independently represents a single bond, —CO—, or —SO₂—.

In General Formula (b0-1), X₀₁ ⁻ is, among the above, preferably an anion represented by General Formula (b0-1-an1).

Preferred specific examples of the anion represented by General Formula (b0-1-an1) are shown below.

In General Formula (b0-1), X₀₁ ⁻ is, among the above, preferably an anion represented by General Formula (b0-1-an4) from the viewpoint of improving sensitivity.

[In the formula, X⁰ represents a bromine atom or an iodine atom. R^(m) represents a hydroxy group, an alkyl group, a fluorine atom, or a chlorine atom, nb1 represents an integer in a range of 1 to 5, and nb2 represents an integer in a range of 0 to 4, where 1≤nb1+nb2≤5 is satisfied. Yb⁰ represents a divalent linking group or a single bond. Vb⁰ represents a single bond, an alkylene group, or a fluorinated alkylene group. R⁰ represents a hydrogen atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorine atom.]

In General Formula (b0-1-an4), X⁰ represents a bromine atom or an iodine atom and is preferably an iodine atom.

In General Formula (b0-1-an4), R^(m) represents a hydroxy group, an alkyl group, a fluorine atom, or a chlorine atom. The alkyl group as R^(m) is preferably an alkyl group having 1 to 5 carbon atoms and more preferably a methyl group or an ethyl group.

In General Formula (b0-1-an4), R^(m) is, among the above, preferably a hydroxy group.

In General Formula (b0-1-an4), nb1 represents an integer in a range of 1 to 5, and nb2 represents an integer in a range of 0 to 4, where 1≤nb1+nb2≤5 is satisfied.

nb1 is preferably an integer in a range of 1 to 3, more preferably 2 or 3 and still more preferably 3.

nb2 is preferably an integer in a range of 0 to 3, more preferably 0 or 1, and still more preferably 0.

In General Formula (b0-1-an4), Yb⁰ represents a divalent linking group or a single bond. Suitable examples of the divalent linking group as Yb⁰ include a divalent linking group containing an oxygen atom.

In a case where Yb⁰ represents a divalent linking group containing an oxygen atom, Yb⁰ may contain an atom other than the oxygen atom. Examples of atoms other than the oxygen atom include a carbon atom, a hydrogen atom, a sulfur atom, and a nitrogen atom.

Examples of divalent linking groups containing an oxygen atom include non-hydrocarbon-based oxygen atom-containing linking groups such as an oxygen atom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonyl group (—O—C(═O)—), an amide bond (—C(═O)—NH—), a carbonyl group (—C(═O)—), or a carbonate bond (—O—C(═O)—O—); and combinations of the above-described non-hydrocarbon-based oxygen atom-containing linking groups with an alkylene group. Furthermore, a sulfonyl group (—SO₂—) may be linked to the combination.

In General Formula (b0-1-an4), Vb⁰ represents an alkylene group, a fluorinated alkylene group, or a single bond.

The alkylene group and the fluorinated alkylene group as Vb⁰ each preferably have 1 to 4 carbon atoms and more preferably 1 to 3 carbon atoms. Examples of the fluorinated alkylene group as Vb⁰ include a group obtained by substituting part or all hydrogen atoms in an alkylene group a fluorine atom. Among them, Vb⁰ is preferably an alkylene group having 1 to 4 carbon atoms, a fluorinated alkylene group having 1 to 4 carbon atoms, or a single bond, and more preferably a group obtained by substituting part of hydrogen atoms of an alkylene group having 1 to 3 carbon atoms with a fluorine atom, or a single bond.

In General Formula (b0), R⁰ represents a hydrogen atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorine atom. R⁰ is preferably a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms and more preferably a fluorine atom.

In General Formula (b0-1), X₀f is more preferably an anion represented by General Formula (b0-an0) from the viewpoint of improving sensitivity.

[In the formula, X⁰ represents a bromine atom or an iodine atom. R^(m) represents a hydroxy group, an alkyl group, a fluorine atom, or a chlorine atom, nb1 represents an integer in a range of 1 to 5, and nb2 represents an integer in a range of 0 to 4, where 1≤nb1+nb2≤5 is satisfied. L⁰¹ and L⁰² each independently represents a single bond, an alkylene group, —O—, —CO—, —OCO—, —COO—, —SO₂—, —N(R^(a))—C(═O)—, —N(R^(a))—, —C(R^(a))(R^(a))—N(R^(a))—, —C(R^(a))(N(R^(a))(R^(a)))—, or —C(═O)—N(R^(a)). Each R^(a) independently represents a hydrogen atom or an alkyl group, z represents an integer in a range of 0 to 10. Vb⁰ represents a single bond, an alkylene group, or a fluorinated alkylene group. R⁰ represents a hydrogen atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorine atom.]

X⁰, R^(m), nb1, nb2, Vb⁰, and R⁰ in General Formula (b0-an0) are each the same as X⁰, R^(m), nb1, nb2, Vb⁰, and R⁰ in General Formula (b0) described above.

In General Formula (b0-an0), L⁰¹ and L⁰² each independently represents a single bond, an alkylene group, —O—, —CO—, —OCO—, —COO—, —SO₂—, —N(R^(a))—C(═O)—, —N(R^(a))—, —C(R^(a))(R^(a))—N(R^(a))—, —C(R^(a))(N(R^(a))(R^(a)))—, or —C(═O)—N(R^(a)). Each R^(a) independently represents a hydrogen atom or an alkyl group.

The alkylene group as L⁰¹ and L⁰² and the alkyl group as R^(a) each have preferably 1 to 4 carbon atoms and more preferably 1 to 3 carbon atoms.

In General Formula (b0-an0), among the above, it is preferable that any one of L⁰¹ and L⁰² is —OCO— or —COO—, and it more preferable that L⁰¹ is —OCO— or —COO and L⁰² is a single bond, —OCO—, or —COO—.

More specifically, in General Formula (b0-an0), -L⁰¹—(CH₂)_(z)-L⁰²-Vb⁰- is preferably —COO-Vb⁰—, —OCO-Vb⁰—, or —COO—(CH₂)_(z)—COO-Vb⁰-.

In General Formula (b0-an0), z represents an integer in a range of 0 to 10, preferably an integer of 0 to 5, and more preferably an integer in a range of 0 to 3.

Specific examples of the anion represented by General Formula (b0-1-an4) are shown below.

Among the above, the compound (B01) is preferably a compound (B011) represented by General Formula (b0-1-1) (hereinafter, also referred to as a “compound (B011)”).

[In the formula, R^(b2) and R^(b3) each independently represent an aryl group which may have a substituent, an alkyl group which may have a substituent, or an alkenyl group which may have a substituent. R^(b2) and R^(b3) may be bonded to each other to form a ring together with a sulfur atom in the formula. X⁰¹¹ represents a fluorine atom or a fluorinated alkyl group. R⁰¹¹ represents a substituent, nb represents an integer of 1 or more, pb represents an integer of 0 or more, qb represents an integer in a range of 0 to 3. However, nb+pb≤qb×2+5 is satisfied. X₀₁ ⁻ represents a counter anion.]

The anion moiety of the compound (B011) is the same as the anion moiety of the compound (B01).

The cation moiety of the compound (B011) is the same as the cation represented by General Formula (ca-b01-1).

Preferred specific examples of the compound (B01) are shown below.

Among the above, the compound (B01) is preferably a compound represented by any of General Formulae (B01-1) to (B01-6), and more preferably a compound represented by any one of General Formulae (B01-1) and (B01-3) to (B01-6).

In the resist composition according to the present embodiment, the compound (B01) may be used alone or in a combination of two or more kinds thereof.

The content of the compound (B01) is preferably in a range of 5 to 40 parts by mass, more preferably in a range of 10 to 40 parts by mass, and still more preferably in a range of 15 to 35 parts by mass, with respect to 100 parts by mass of the component (A1).

In a case where the content of the compound (B01) is equal to or larger than the lower limit value of the above preferred range, the lithography characteristics such as sensitivity, resolution performance, and a linewise roughness (LWR) reduction property are further improved in the resist pattern formation. On the other hand, in a case where it is equal to or smaller than the upper limit value of the preferred range, a homogeneous solution is easily obtained when each component of the resist composition is dissolved in an organic solvent, and the storage stability as a resist composition is further improved.

In a case where the content of the compound (B01) has the anion represented by the above general formula (b0-1-an4), the content of compound (B01) is preferably in a range of 5 to 40 parts by mass, more preferably in a range of 10 to 40 parts by mass, and still more preferably in a range of 15 to 40 parts by mass, with respect to 100 parts by mass of the component (A1).

In a case where the content of the compound (B01) is equal to or larger than the lower limit value of the above preferred range, sensitivity is further improved. On the other hand, in a case where it is equal to or smaller than the upper limit value of the preferred range, a homogeneous solution is easily obtained when each component of the resist composition is dissolved in an organic solvent, and the storage stability as a resist composition is further improved.

<<Compound (B02)>>

The compound (B02) is a compound represented by General Formula (b0-2).

In General Formula (b0-2), R^(b4) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group. R^(b5) represents an aryl group which may have a substituent, an alkyl group which may have a substituent, an alkenyl group which may have a substituent. X₀₂ ⁻ represents a counter anion.]

In Regard to Cation Moiety

In General Formula (b0-2), R^(b4) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group, and examples thereof include the same one as R^(b1) in General Formula (b0-1).

In General Formula (b0-2), R^(b5) represents an aryl group which may have a substituent, an alkyl group which may have a substituent, or an alkenyl group which may have a substituent, and examples thereof include the same ones as R^(b2) and R^(b3) in General Formula (b0-2).

In General Formula (b0-2), R^(b4) is preferably a phenyl group having a group obtained by substituting part or all hydrogen atoms of a phenyl group having a fluorine atom or an alkyl group having 1 to 5 carbon atoms with a fluorine atom, and more preferably a phenyl group having a fluorine atom.

In General Formula (b0-2), R^(b5) is preferably a phenyl group having a group obtained by substituting part or all hydrogen atoms of a phenyl group having a fluorine atom or an alkyl group having 1 to 5 carbon atoms with a fluorine atom, and more preferably a phenyl group having a fluorine atom.

Preferred specific examples of the cation moiety of the compound (B02) are shown below.

In Regard to Anion Moiety

In General Formula (b0-2), X₀₂ ⁻ represents a counter anion, and examples thereof include the same one as X₀f in General Formula (b0-1).

Preferred specific examples of the compound (B02) are shown below.

In the resist composition according to the present embodiment, the compound (B02) may be used alone or in a combination of two or more kinds thereof.

The content of the compound (B02) is preferably in a range of 5 to 40 parts by mass, more preferably in a range of 10 to 40 parts by mass, and still more preferably in a range of 15 to 35 parts by mass, with respect to 100 parts by mass of the component (A1).

In a case where the content of the compound (B02) is equal to or larger than the lower limit value of the above preferred range, the lithography characteristics such as sensitivity, resolution performance, and a linewise roughness (LWR) reduction property are further improved in the resist pattern formation. On the other hand, in a case where it is equal to or smaller than the upper limit value of the preferred range, a homogeneous solution is easily obtained when each component of the resist composition is dissolved in an organic solvent, and the storage stability as a resist composition is further improved.

In the resist composition according to the present embodiment, only one of the compound (B01) and the compound (B02) may be used, or the compound (B01) and the compound (B02) may be used in combination.

In a case where the compound (B01) and the compound (B02) are used in combination, the total content of the compound (B01) and the compound (B02) is preferably in a range of 5 to 40 parts by mass, more preferably in a range of 10 to 40 parts by mass, and still more preferably in a range of 15 to 40 parts by mass, with respect to 100 parts by mass of the component (A1).

In a case where the total content of the compound (B01) and the compound (B02) is equal to or larger than the lower limit value of the above preferred range, the lithography characteristics such as sensitivity, resolution performance, and a linewise roughness (LWR) reduction property are further improved in the resist pattern formation. On the other hand, in a case where it is equal to or smaller than the upper limit value of the preferred range, a homogeneous solution is easily obtained when each component of the resist composition is dissolved in an organic solvent, and the storage stability as a resist composition is further improved.

<<Component (B2)>>

The resist composition according to the present embodiment may contain an acid generator component (hereinafter, also referred to as a “component (B2)”) other than the compound (B01) and the compound (B02) described above as long as the effects of the present invention are not impaired.

The component (B2) is not particularly limited, and those which have been proposed so far as an acid generator for a chemically amplified resist composition in the related art can be used.

Examples of such an acid generator are numerous and include onium salt-based acid generators such as an iodonium salt and a sulfonium salt; oxime sulfonate-based acid generators; diazomethane-based acid generators such as bisalkyl or bisaryl sulfonyl diazomethanes and poly(bis-sulfonyl)diazomethanes; nitrobenzyl sulfonate-based acid generators; imino sulfonate-based acid generators; and disulfone-based acid generators.

Examples of the onium salt-based acid generator include a compound consisting of X₀₁′ in General Formula (b0-1) described above and a cation represented by any one of Chemical Formulae (ca-1-1) to (ca-1-93) described below.

In the following chemical formulae, g3 indicates the number of repetitions, and g3 represents an integer in a range of 0 to 20. R″²⁰¹ represents a hydrogen atom or a substituent. Examples of the substituent include an alkyl group, a halogen atom other than the fluorine atom, a halogenated alkyl group other than the fluorinated alkyl group, a carbonyl group, a cyano group, an amino group, and an aryl group.

[In the formulae, g2 and g3 indicate the numbers of repetitions, g2 represents an integer in a range of 0 to 20, and g3 represents an integer in a range of 0 to 20.]

[In the formula, R″²⁰¹ represents a hydrogen atom or a substituent, and examples of the substituent include the same substituent as that exemplified as the substituent which may be contained in R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹².]

In the resist composition according to the present embodiment, the component (B2) may be used alone or in a combination of two or more kinds thereof.

In a case where the resist composition contains the component (B2), the content of the component (B2) in the resist composition is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 20 parts by mass or less, with respect to 100 parts by mass of the component (A1).

<Other Components>

The resist composition according to the present embodiment may further contain other components in addition to the component (A) and the component (B) described above. Examples of the other components include a component (D), a component (E), a component (F), and a component (S), which are described below.

<<Base component (D)>>

The resist composition according to the present embodiment may further contain, a base component (a component (D)) that traps (that is, controls the acid diffusion) an acid generated from the component (B) upon exposure. The component (D) acts as a quencher (an acid diffusion controlling agent) which traps the acid generated in the resist composition upon exposure.

Examples of the component (D) include a photodecomposable base (D1) having an acid diffusion controllability (hereinafter, referred to as a “component (D1)”) which is lost by the decomposition upon exposure and a nitrogen-containing organic compound (D2) (hereinafter, referred to as a “component (D2)”) which does not correspond to the component (D1). Among these, the photodecomposable base (the component (D1)) is preferable since it is easy to enhance the characteristics of high sensitivity, roughness reduction, and suppression of the occurrence of coating defects.

In Regard to Component (D1)

In a case where a resist composition containing the component (D1) is obtained, the contrast between the exposed portions and unexposed portions of the resist film can be further improved at the time of forming a resist pattern.

The component (D1) is not particularly limited as long as it is decomposed upon exposure and loses the acid diffusion controllability. The component (D1) is preferably one or more compounds selected from the group consisting of a compound represented by General Formula (d1-1) (hereinafter, referred to as a “component (d1-1)”), a compound represented by General Formula (d1-2) (hereinafter, referred to as a “component (d1-2)”), and a compound represented by General Formula (d1-3) (hereinafter, referred to as a “component (d1-3)”).

In the exposed portions of the resist film, the components (d1-1) to (d1-3) are decomposed and then lose the acid diffusion controllability (basicity), and thus they cannot act as a quencher, while acting as a quencher in the unexposed portions of the resist film.

[In the formulae, Rd¹ to Rd⁴ represents cyclic groups which may have a substituent, chain-like alkyl groups which may have a substituent, or chain-like alkenyl groups which may have a substituent. Here, the carbon atom adjacent to the S atom as Rd² in General Formula (d1-2) has no fluorine atom bonded thereto. Yd¹ represents a single bond or a divalent linking group, m represents an integer of 1 or more, and each M^(m+) independently represents an m-valent organic cation].

{Component (d1-1)}

Anion Moiety

In General Formula (d1-1), Rd¹ represents a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent, and examples of each of them include the same one as R′²⁰¹.

Among these, Rd¹ is preferably an aromatic hydrocarbon group which may have a substituent, an aliphatic cyclic group which may have a substituent, or a chain-like alkyl group which may have a substituent. Examples of the substituent which may be contained in these groups include a hydroxyl group, an oxo group, an alkyl group, an aryl group, a fluorine atom, an iodine atom, a bromine atom, a fluorinated alkyl group, lactone-containing cyclic groups each represented by any of General Formulae (a2-r-1) to (a2-r-7), an ether bond, an ester bond, and a combination thereof. In a case where an ether bond or an ester bond is included as the substituent, the substituent may be bonded via an alkylene group, and the substituent in this case is preferably linking groups each represented by General Formulae (y-a1-1) to (y-a1-5).

Suitable examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, and a polycyclic structure (a polycyclic structure consisting of a bicyclooctane skeleton and a ring structure other than the bicyclooctane skeleton).

The aliphatic cyclic group is preferably a group obtained by removing one or more hydrogen atoms from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, and specific examples thereof include a linear alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, or a decyl group, and a branched alkyl group such as a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, or a 4-methylpentyl group.

In a case where the chain-like alkyl group is a fluorinated alkyl group having a fluorine atom or a fluorinated alkyl group as a substituent, the fluorinated alkyl group preferably has 1 to 11 carbon atoms, more preferably 1 to 8 carbon atoms, and still more preferably 1 to 4 carbon atoms. The fluorinated alkyl group may contain an atom other than the fluorine atom. Examples of the atom other than the fluorine atom include an oxygen atom, a sulfur atom, and a nitrogen atom.

Preferred specific examples of the anion moiety of the component (d1-1) are shown below.

Cation Moiety

In General Formula (d1-1), M^(m+) represents an m-valent organic cation. Suitable examples of the organic cation as M^(m+) include the same ones as the cations each represented by Chemical Formulae (ca-b01-11) to (ca-b01-22) and (ca-1-1) to (ca-1-93). Among them, the same ones as the cation moiety in General Formula (b0-1) described above and the cation moiety in General Formula (b0-2) described above are more preferable, and cations each represented by Chemical Formulae (ca-b01-11) to (ca-b01-24) are more preferable.

That is, a combination in which both the component (B) and the component (D1) described above have a fluorine atom in the cation moiety is preferable, and specifically, a combination of the compound (B01) or compound (B02) with the component (d1-1) having a fluorine atom in the cation moiety.

From the viewpoint of improving sensitivity, the component (d1-1) preferably contains a compound (hereinafter, also referred to as a “component (D0)”) represented by General Formula (d0-1).

[In the formula, X⁰ represents a bromine atom or an iodine atom. R^(m) represents a hydroxy group, an alkyl group, a fluorine atom, or a chlorine atom, nd1 represents an integer in a range of 1 to 5, and nd2 represents an integer in a range of 0 to 4, where 1≤nd1+nd2≤5 is satisfied. Yd⁰ represents a divalent linking group or a single bond, M^(m+) represents an m-valent organic cation, m represents an integer of 1 or more.]

{Anion Moiety of Component (D0)}

In General Formula (d0-1), X⁰ represents a bromine atom or an iodine atom and is preferably an iodine atom.

In General Formula (d0-1), R^(m) represents a hydroxy group, an alkyl group, a fluorine atom, or a chlorine atom. The alkyl group as R^(m) is preferably an alkyl group having 1 to 5 carbon atoms and more preferably a methyl group or an ethyl group.

In General Formula (d0-1), nd1 represents an integer in a range of 1 to 5, and nd2 represents an integer in a range of 0 to 4, where 1 A nd1+nd2≤5 is satisfied.

nd1 is preferably an integer in a range of 1 to 3, more preferably 2 or 3, and still more preferably 3, from the viewpoint of radiation absorbability.

nd2 is preferably an integer in a range of 0 to 3, more preferably 0 or 1, and still more preferably 0.

In General Formula (d0-1), Yd⁰ represents a divalent linking group or a single bond. Suitable examples of the divalent linking group as Yd⁰ include a divalent linking group containing an oxygen atom.

In a case where Yd⁰ represents a divalent linking group containing an oxygen atom, Yd⁰ may contain an atom other than the oxygen atom. Examples of atoms other than the oxygen atom include a carbon atom, a hydrogen atom, a sulfur atom, and a nitrogen atom.

Examples of the divalent linking group containing an oxygen atom include a non-hydrocarbon-based oxygen atom-containing linking group such as an oxygen atom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonyl group (—O—C(═O)—), an amide bond (—C(═O)—NH—), a carbonyl group (—C(═O)—), or a carbonate bond (—O—C(═O)—O—); a combination of the above-described non-hydrocarbon-based oxygen atom-containing linking group with an alkylene group; and a combination of a non-hydrocarbon-based oxygen atom-containing linking group with a fluorinated alkylene group. Furthermore, a sulfonyl group (—SO₂—) may be linked to the combination.

Yd⁰ is preferably a divalent linking group containing an oxygen atom or a single bond, and more preferably a single bond.

Specific examples of the anion moiety of the component (D0) are shown below.

{Cation Moiety of Component (D0)}

In General Formula (d0-1), M^(m+) represents an m-valent organic cation.

Suitable examples of the organic cation as M^(m+) include the same ones as the cations each represented by Chemical Formulae (ca-b01-11) to (ca-b01-22) and (ca-1-1) to (ca-1-93). Among them, the same ones as the cation moiety in General Formula (b0-1) described above and the cation moiety in General Formula (b0-2) described above are more preferable, and cations each represented by Chemical Formulae (ca-b01-11) to (ca-b01-24) are more preferable.

The compound (D0) is preferably a compound represented by General Formula (d0-1-1).

[In the formula, X⁰, R^(m), nd1, and nd2 are the same as X⁰, R^(m), nd1, and nd2 in General Formula (d0-1). R²⁰¹ to R²⁰³ are the same as R²⁰¹ to R²⁰³ in General Formula (ca-1).]

Specific examples of the component (D0) are shown below but are not limited thereto.

One kind of the component (d1-1) may be used alone, or a combination of two or more kinds thereof may be used.

{Component (d1-2)}

Anion Moiety

In General Formula (d1-2), Rd² represents a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent, and examples thereof include the same one as R′²⁰¹.

Here, the carbon atom adjacent to the S atom in Rd² has no fluorine atom bonded thereto (the carbon atom adjacent to the S atom in Rd² is not substituted with a fluorine atom). As a result, the anion of the component (d1-2) becomes an appropriately weak acid anion, thereby improving the quenching ability of the component (D).

Rd² is preferably a chain-like alkyl group which may have a substituent or an aliphatic cyclic group which may have a substituent. The chain-like alkyl group preferably has 1 to 10 carbon atoms and more preferably 3 to 10 carbon atoms. The aliphatic cyclic group is more preferably a group (which may have a substituent) in which one or more hydrogen atoms have been removed from adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, or the like; and a group in which one or more hydrogen atoms have been removed from camphor or the like.

The hydrocarbon group as Rd² may have a substituent. Examples of the substituent include the same one as the substituent which may be contained in the hydrocarbon group (an aromatic hydrocarbon group, an aliphatic cyclic group, or a chain-like alkyl group) as Rd¹ in General Formula (d1-1).

Preferred specific examples of the anion moiety of the component (d1-2) are shown below.

Cation Moiety

In General Formula (d1-2), M^(m+) represents an m-valent organic cation and is the same as M^(m+) in General Formula (d1-1).

One kind of the component (d1-2) may be used alone, or a combination of two or more kinds thereof may be used.

{Component (d1-3)}

Anion Moiety

In General Formula (d1-3), Rd³ represents a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent, examples thereof include the same one as R′²⁰¹, and a cyclic group containing a fluorine atom, a chain-like alkyl group, or a chain-like alkenyl group is preferable. Among them, a fluorinated alkyl group is preferable, and the same one as the fluorinated alkyl group described above as Rd¹ is more preferable.

In General Formula (d1-3), Rd⁴ represents a cyclic group which may have a substituent, a chain-like alkyl group which may have a substituent, or a chain-like alkenyl group which may have a substituent, and examples thereof include the same one as R′²⁰¹.

Among them, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an alkenyl group which may have a substituent, or a cyclic group which may have a substituent is preferable.

The alkyl group as Rd⁴ is preferably a linear or branched alkyl group having 1 to carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. Part of hydrogen atoms in the alkyl group as Rd⁴ may be substituted with a hydroxyl group, a cyano group, or the like.

The alkoxy group as Rd⁴ is preferably an alkoxy group having 1 to 5 carbon atoms, and specific examples of the alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, and a tert-butoxy group. Among these, a methoxy group and an ethoxy group are preferable.

Examples of the alkenyl group as Rd⁴ include the same one as R′²⁰¹, and a vinyl group, a propenyl group (an allyl group), a 1-methylpropenyl group, or a 2-methylpropenyl group is preferable. These groups may have an alkyl group having 1 to carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms as a substituent.

Examples of the cyclic group as Rd⁴ include the same one as the cyclic group described above as R′²⁰¹, and the cyclic group is preferably an alicyclic group obtained by removing one or more hydrogen atoms from a cycloalkane such as cyclopentane, cyclohexane, adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane, or an aromatic group such as a phenyl group or a naphthyl group.

In a case where Rd⁴ represents an alicyclic group, the resist composition can be satisfactorily dissolved in an organic solvent, thereby improving lithography characteristics. In a case where Rd⁴ is an aromatic group, the resist composition is excellent in light absorption efficiency and thus has good sensitivity and lithography characteristics in the lithography using EUV or the like as a light source for exposure.

In General Formula (d1-3), Yd¹ represents a single bond or a divalent linking group.

The divalent linking group as Yd¹ is not particularly limited, and examples thereof include a divalent hydrocarbon group (an aliphatic hydrocarbon group or an aromatic hydrocarbon group) which may have a substituent and a divalent linking group containing a hetero atom. Examples of each of them include the same ones as the divalent hydrocarbon group which may have a substituent and the divalent linking group containing a hetero atom, which are mentioned in the explanation of the divalent linking group as Ya²¹ in General Formula (a2-1).

Yd¹ is preferably a carbonyl group, an ester bond, an amide bond, an alkylene group, or a combination of these. The alkylene group is more preferably a linear or branched alkylene group and still more preferably a methylene group or an ethylene group.

Preferred specific examples of the anion moiety for the component (d1-3) are shown below.

Cation Moiety

In General Formula (d1-3), M^(m+) represents an m-valent organic cation and is the same as M^(m+) in General Formula (d1-1).

One kind of the component (d1-3) may be used alone, or a combination of two or more kinds thereof may be used.

As the component (D1), any one of the above components (d1-1) to (d1-3) may be used alone, or a combination of two or more thereof may be used.

Among the above, the component (D1) is preferably the component (d1-1).

In a case where the resist composition contains the component (D1), the content of the component (D1) in the resist composition is preferably in a range of 0.5 to 20 parts by mass, more preferably in a range of 1 to 15 parts by mass, and still more preferably in a range of 2 to 10 parts by mass with respect to 100 parts by mass of the component (A1).

In a case where the content of the component (D1) is equal to or larger than the preferred lower limit value, particularly excellent lithography characteristics and a particularly excellent resist pattern shape are easily obtained. On the other hand, in a case where the content of the component (D1) is equal to or smaller than the upper limit value, the sensitivity can be maintained satisfactorily and the throughput is also excellent.

In a case where the resist composition contains the component (D0), the content of the component (D0) in the resist composition is preferably in a range of 0.5 to 20 parts by mass, more preferably in a range of 1 to 15 parts by mass, and still more preferably in a range of 2 to 10 parts by mass with respect to 100 parts by mass of the component (A1).

In a case where the content of the component (D0) is equal to or larger than the preferred lower limit value, particularly excellent lithography characteristics and a particularly excellent resist pattern shape are easily obtained. On the other hand, in a case where the content of the component (D0) is equal to or smaller than the upper limit value, the sensitivity can be maintained satisfactorily and the throughput is also excellent.

Method of Producing Component (D1):

The methods of producing the components (d1-1) and (d1-2) are not particularly limited, and the components (d1-1) and (d1-2) can be produced by conventionally known methods.

Further, the method of producing the component (d1-3) is not particularly limited, and the component (d1-3) can be produced in the same manner as disclosed in United States Patent Application, Publication No. 2012-0149916.

In Regard to Component (D2)

The component (D) may contain a nitrogen-containing organic compound component (hereinafter, referred to as a “component (D2)”) which does not correspond to the above-described component (D1).

The component (D2) is not particularly limited as long as it acts as an acid diffusion controlling agent and does not correspond to the component (D1), and any conventionally known compound may be used. Among the above, an aliphatic amine is preferable, among which a secondary aliphatic amine or a tertiary aliphatic amine is more preferable.

An aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.

Examples of the aliphatic amine include an amine obtained by substituting at least one hydrogen atom of ammonia (NH₃) with an alkyl group or hydroxyalkyl group having 12 or fewer carbon atoms (an alkylamine or an alkyl alcohol amine) and a cyclic amine.

Specific examples of alkyl amines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, and n-decylamine; dialkylamines such as diethylamine, di-n-propylamine, di-n-heptylamine, di-n-octylamine, and dicyclohexylamine; trialkylamines such as trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkyl alcohol amines such as diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n-octanolamine, and tri-n-octanolamine. Among these, a trialkylamine having 5 to 10 carbon atoms is preferable, and tri-n-pentylamine or tri-n-octylamine is particularly preferable.

Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be a monocyclic compound (an aliphatic monocyclic amine), or a polycyclic compound (an aliphatic polycyclic amine).

Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.

The aliphatic polycyclic amine preferably has 6 to 10 carbon atoms, and specific examples thereof include 1,5-diazabicyclo[4.3.0]-5-nonene, 1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and 1,4-diazabicyclo[2.2.2]octane.

Examples of other aliphatic amines include tris(2-methoxymethoxyethyl)amine, tris {2-(2-methoxyethoxy)ethyl} amine, tris {2-(2-methoxyethoxymethoxy)ethyl} amine, tris {2-(1-methoxyethoxy)ethyl} amine, tris {2-(1-ethoxyethoxy)ethyl} amine, tris {2-(1-ethoxypropoxy)ethyl} amine, tris[2-{2-(2-hydroxyethoxy)ethoxy} ethyl] amine and triethanolamine triacetate, and triethanolamine triacetate is preferable.

In addition, as the component (D2), an aromatic amine may be used.

Examples of the aromatic amine include 4-dimethylaminopyridine, pyrrole, indole, pyrazole, imidazole, and derivatives thereof, tribenzylamine, 2,6-diisopropylaniline, and N-tert-butoxycarbonylpyrrolidine.

One kind of the component (D2) may be used alone, or a combination of two or more kinds thereof may be used.

In a case where the resist composition contains the component (D2), the content of the component (D2) in the resist composition is typically in a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the component (A1). By setting the content within the above range, the resist pattern shape, the post-exposure temporal stability, and the like are improved.

<<At Least One Compound (E) Selected from Group Consisting of Organic Carboxylic Acid, Phosphorus Oxo Acid, and Derivatives Thereof>>

For the purpose of preventing any deterioration in sensitivity, and improving the resist pattern shape, the post-exposure temporal stability, and the like, the resist composition according to the present embodiment may contain at least one compound (E) (hereinafter referred to as a component (E)) selected from the group consisting of an organic carboxylic acid, and a phosphorus oxo acid and a derivative thereof, as an optional component.

Examples of suitable organic carboxylic acids include acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, and salicylic acid.

Examples of the phosphorus oxo acid include phosphoric acid, phosphonic acid, and phosphinic acid. Among these, phosphonic acid is particularly preferable.

Examples of the phosphorus oxo acid derivative include an ester obtained by substituting a hydrogen atom in the above-described oxo acid with a hydrocarbon group. Examples of the hydrocarbon group include an alkyl group having 1 to 5 carbon atoms and an aryl group having 6 to 15 carbon atoms.

Examples of phosphoric acid derivatives include phosphoric acid esters such as di-n-butyl phosphate and diphenyl phosphate.

Examples of phosphonic acid derivatives include phosphonic acid esters such as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonic acid, diphenyl phosphonate, and dibenzyl phosphonate.

Examples of phosphinic acid derivatives include phosphinic acid esters and phenylphosphinic acid.

In the resist composition according to the present embodiment, the component (E) may be used alone or in a combination of two or more kinds thereof.

In a case where the resist composition contains the component (E), the content of the component (E) is typically in a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the component (A1).

<<Fluorine Additive Component (F)>>

The resist composition according to the present embodiment may include a fluorine additive component (hereinafter, referred to as a “component (F)”) in order to impart water repellency to the resist film or to improve lithography characteristics.

As the component (F), a fluorine-containing polymeric compound described in Japanese Unexamined Patent Application, First Publication No. 2010-002870, Japanese Unexamined Patent Application, First Publication No. 2010-032994, Japanese Unexamined Patent Application, First Publication No. 2010-277043, Japanese Unexamined Patent Application, First Publication No. 2011-13569, and Japanese Unexamined Patent Application, First Publication No. 2011-128226 can be mentioned.

Specific examples of the component (F) include polymers having a constitutional unit (f1) represented by General Formula (f1-1) shown below. This polymer is preferably a polymer (homopolymer) consisting of only a constitutional unit (f1) represented by General Formula (f1-1) shown below; a copolymer of the constitutional unit (f1) and the constitutional unit (a1); and a copolymer of the constitutional unit (f1), a constitutional unit derived from acrylic acid or methacrylic acid, and the above-described constitutional unit (a1). The constitutional unit (a1) to be copolymerized with the constitutional unit (f1) is preferably a constitutional unit derived from 1-ethyl-1-cyclooctyl (meth)acrylate or a constitutional unit derived from 1-methyl-1-adamantyl (meth)acrylate.

[In the formula, R has the same definition as described above. Rf¹⁰² and Rf¹⁰³ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms, and Rf¹⁰² and Rf¹⁰³ may be the same or different from each other, nf¹ represents an integer in a range of 0 to 5 and Rf¹⁰¹ represents an organic group containing a fluorine atom.]

In General Formula (f1-1), R bonded to the carbon atom at the α-position has the same definition as described above. R is preferably a hydrogen atom or a methyl group.

In General Formula (f1-1), the halogen atom as Rf¹⁰² and Rf¹⁰³ is preferably a fluorine atom. Examples of the alkyl group having 1 to 5 carbon atoms as Rf¹⁰² and Rf¹⁰³ include the same one as the alkyl group having 1 to 5 carbon atoms as R, and a methyl group or an ethyl group is preferable. Specific examples of the halogenated alkyl group having 1 to 5 carbon atoms as Rf¹⁰² and Rf¹⁰³ include a group obtained by substituting part or all hydrogen atoms of an alkyl group having 1 to 5 carbon atoms with a halogen atom. The halogen atom is preferably a fluorine atom. Among the above, Rf¹⁰² and Rf¹⁰³ is preferably a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 5 carbon atoms and more preferably a hydrogen atom, a fluorine atom, a methyl group, or an ethyl group.

In General Formula (f1-1), nf¹ represents an integer in a range of 0 to 5, preferably an integer in a range of 0 to 3, and more preferably an integer of 1 or 2.

In General Formula (f1-1), Rf¹⁰¹ represents an organic group containing a fluorine atom and is preferably a hydrocarbon group containing a fluorine atom.

The hydrocarbon group containing a fluorine atom may be linear, branched, or cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and particularly preferably 1 to 10 carbon atoms.

In addition, in the hydrocarbon group containing a fluorine atom, 25% or more of the hydrogen atoms in the hydrocarbon group are preferably fluorinated, more preferably 50% or more are fluorinated, and particularly preferably 60% or more are fluorinated since the hydrophobicity of the resist film during immersion exposure is enhanced.

Among them, Rf¹⁰¹ is preferably a fluorinated hydrocarbon group having 1 to 6 carbon atoms and particularly preferably a trifluoromethyl group, —CH₂—CF₃, —CH₂—CF₂—CF₃, —CH(CF₃)₂, —CH₂—CH₂—CF₃, or —CH₂—CH₂—CF₂—CF₂—CF₂—CF₃.

The weight average molecular weight (Mw) (based on the polystyrene-equivalent value determined by gel permeation chromatography) of the component (F) is preferably in a range of 1,000 to 50,000, more preferably in a range of 5,000 to 40,000, and most preferably in a range of 10,000 to 30,000. In a case where the weight average molecular weight is equal to or smaller than the upper limit value of this range, a resist solvent solubility sufficient to be used as a resist is exhibited. On the other hand, in a case where it is equal to or larger than the lower limit value of this range, the water repellency of the resist film is excellent.

Further, the dispersity (Mw/Mn) of the component (F) is preferably in a range of 1.0 to 5.0, more preferably in a range of 1.0 to 3.0, and most preferably in a range of 1.0 to 2.5.

In the resist composition according to the present embodiment, the component (F) may be used alone or in a combination of two or more kinds thereof.

In a case where the resist composition contains the component (F), the content of the component (F) to be used is typically at a proportion of 0.5 to 10 parts by mass, with respect to 100 parts by mass of the component (A1).

<<Organic Solvent Component (S)>>

The resist composition according to the present embodiment may be produced by dissolving the resist materials in an organic solvent component (hereinafter, referred to as a “component (S)”).

The component (S) may be any organic solvent which can dissolve the respective components to give a homogeneous solution, and any organic solvent can be appropriately selected from those which are conventionally known as solvents for a chemically amplified resist composition and then used.

Examples of the component (S) include lactones such as y-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols, such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol; compounds having an ester bond, such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, and dipropylene glycol monoacetate, polyhydric alcohol derivatives such as compounds having an ether bond, such as a monoalkyl ether (such as monomethyl ether, monoethyl ether, monopropyl ether or monobutyl ether) or monophenyl ether of any of these polyhydric alcohols or compounds having an ester bond (among these, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferable); cyclic ethers such as dioxane; esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl ethoxypropionate; aromatic organic solvents such as anisole, ethylbenzylether, cresylmethylether, diphenylether, dibenzylether, phenetole, butylphenylether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene and mesitylene; and dimethylsulfoxide (DMSO).

In the resist composition according to the present embodiment, the component (S) may be used alone or as a mixed solvent of two or more kinds thereof. Among these, PGMEA, PGME, γ-butyrolactone, EL, and cyclohexanone are preferable.

Further, a mixed solvent obtained by mixing PGMEA with a polar solvent is also preferable as the component (S). The blending ratio (mass ratio) of the mixed solvent can be suitably determined, taking into consideration the compatibility of the PGMEA with the polar solvent, but is preferably in a range of 1:9 to 9:1 and more preferably in a range of 2:8 to 8:2.

More specifically, in a case where EL or cyclohexanone is blended as the polar solvent, the PGMEA:EL or cyclohexanone mass ratio is preferably in a range of 1:9 to 9:1 and more preferably in a range of 2:8 to 8:2. Alternatively, in a case where PGME is blended as the polar solvent, the PGMEA:PGME mass ratio is preferably in a range of 1:9 to 9:1, more preferably in a range of 2:8 to 8:2, and still more preferably in a range of 3:7 to 7:3. Furthermore, a mixed solvent of PGMEA, PGME, and cyclohexanone is also preferable.

Further, the component (S) is also preferably a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone. In this case, as the mixing ratio, the mass ratio of the former to the latter is preferably in a range of 70:30 to 95:5.

The amount of the component (S) to be used is not particularly limited and is suitably set, depending on a thickness of a film to be coated, to a concentration at which the component (S) can be applied onto a substrate or the like. Generally, the component (S) is used such that the solid content concentration of the resist composition is in a range of 0.1% to 20% by mass and preferably in a range of 0.2% to 15% by mass.

As desired, other miscible additives can also be added to the resist composition according to the present embodiment. For example, for improving the performance of the resist film, an additive resin, a dissolution, a plasticizer, a stabilizer, a colorant, a halation prevention agent, and a dye can be suitably contained therein.

After dissolving the resist material in the component (S), the resist composition according to the present embodiment may be subjected to removal of impurities and the like by using a porous polyimide film, a porous polyamideimide film, or the like. For example, the resist composition may be filtered using a filter made of a porous polyimide film, a filter made of a porous polyamideimide film, or a filter made of a porous polyimide film and a porous polyamideimide film. Examples of the porous polyimide film and the porous polyamideimide film include those described in Japanese Unexamined Patent Application, First Publication No. 2016-155121.

The resist composition according to the present embodiment described above contains a resin component (A1) having the above-described constitutional unit (a01) and the compound (B01) or compound (B02).

Since the constitutional unit (a01) has both an acid dissociable group and a phenolic hydroxyl group, the content rate of the phenolic hydroxyl group can be increased without reducing the content of the acid dissociable group in the resin component (A1). As a result, sensitivity can be improved without reducing resolution. Further, the increase of the phenolic hydroxyl group in the resin component (A1) improves the affinity with the developing solution, and thus the fine resolution can be improved.

In addition, since the cation moiety of the compound (B01) and the compound (B02) is a cation having a fluorine atom or a fluorinated alkyl group, the reactivity of decomposing a cation moiety upon exposure is enhanced, which increases sensitivity due to the improvement of acid generation efficiency.

Further, the uniformity of the distribution of the acid generator component in the resist film is improved by the interaction between the phenolic hydroxyl group in the constitutional unit (a01) and the fluorine atom contained in the cation moiety of the compound (B01) and the compound (B02), and the roughness reduction property is improved.

According to such a resist composition according to the present embodiment, all of the sensitivity, the resolution, and the roughness reducing property are improved by the synergistic effect of the resin component (A1) having the constitutional unit (a01) and the compound (B01) or the compound (B02).

(Method of Forming Resist Pattern)

A method of forming a resist pattern according to the second aspect according to the present invention is a method including a step of forming a resist film on a support using the resist composition according to the first aspect of the present invention described above, a step of exposing the resist film, and a step of developing the exposed resist film to form a resist pattern.

Examples of one embodiment of such a method of forming a resist pattern include a method of forming a resist pattern carried out as described below.

First, the resist composition of the above-described embodiment is applied onto a support with a spinner or the like, and a baking (post-apply baking (PAB)) treatment is carried out, for example, under a temperature condition in a range of 80° C. to 150° C. for to 120 seconds and preferably for 60 to 90 seconds to form a resist film.

Following the selective exposure carried out on the resist film by, for example, exposure through a mask (mask pattern) having a predetermined pattern formed on the mask by using an exposure apparatus such as an electron beam lithography apparatus or an EUV exposure apparatus, or direct irradiation of the resist film for drawing with an electron beam without using a mask pattern, baking treatment (post-exposure baking (PEB)) is carried out, for example, under a temperature condition in a range of 80° C. to 150° C. for 40 to 120 seconds and preferably 60 to 90 seconds.

Next, the resist film is subjected to a developing treatment. The developing treatment is carried out using an alkali developing solution in a case of an alkali developing process, and a developing solution containing an organic solvent (organic developing solution) in a case of a solvent developing process.

After the developing treatment, it is preferable to carry out a rinse treatment. As the rinse treatment, water rinsing using pure water is preferable in a case of an alkali developing process, and rinsing using a rinse liquid containing an organic solvent is preferable in a case of a solvent developing process.

In a case of a solvent developing process, after the developing treatment or the rinsing, the developing solution or the rinse liquid remaining on the pattern can be removed by a treatment using a supercritical fluid.

After the developing treatment or the rinse treatment, drying is carried out. As desired, baking treatment (post-baking) can be carried out following the developing treatment.

In this manner, a resist pattern can be formed.

The support is not specifically limited, and a conventionally known support can be used.

For example, substrates for electronic components, and such substrates having predetermined wiring patterns formed thereon can be used. Specific examples of the material of the substrate include metals such as silicon wafer, copper, chromium, iron and aluminum; and glass. Suitable materials for the wiring pattern include copper, aluminum, nickel, and gold.

Further, as the support, any support having the substrate described above, on which an inorganic and/or organic film is provided, may be used. Examples of the inorganic film include an inorganic antireflection film (an inorganic BARC). Examples of the organic film include an organic antireflection film (an organic BARC) and an organic film such as a lower-layer organic film used in a multilayer resist method.

Here, the multilayer resist method is a method in which at least one layer of an organic film (lower-layer organic film) and at least one layer of a resist film (upper-layer resist film) are provided on a substrate, and a resist pattern formed on the upper-layer resist film is used as a mask to carry out patterning of the lower-layer organic film.

This method is considered as being capable of forming a pattern with a high aspect ratio. More specifically, in the multilayer resist method, a desired thickness can be ensured by the lower-layer organic film, and as a result, the thickness of the resist film can be reduced, and an extremely fine pattern with a high aspect ratio can be formed.

The multilayer resist method is classified into a method in which a double-layer structure consisting of an upper-layer resist film and a lower-layer organic film is formed (double-layer resist method), and a method in which a multilayer structure having at least three layers consisting of an upper-layer resist film, a lower-layer organic film and at least one intermediate layer (thin metal film or the like) provided between the upper-layer resist film and the lower-layer organic film (triple-layer resist method).

The wavelength to be used for exposure is not particularly limited and the exposure can be carried out using radiation such as an ArF excimer laser, a KrF excimer laser, an F₂ excimer laser, an extreme ultraviolet ray (EUV), a vacuum ultraviolet ray (VUV), an electron beam (EB), an X-ray, or a soft X-ray. The resist composition is highly useful for a KrF excimer laser, an ArF excimer laser, EB, or EUV, more useful for an ArF excimer laser, EB or EUV, and particularly useful for EB or EUV. That is, the method of forming a resist pattern according to the present embodiment is a method particularly useful in a case where the step of exposing the resist film includes an operation of exposing the resist film to an extreme ultraviolet ray (EUV) or an electron beam (EB).

The exposure of the resist film can be a general exposure (dry exposure) carried out in air or an inert gas such as nitrogen, or liquid immersion exposure (liquid immersion lithography).

The liquid immersion lithography is an exposure method in which the region between the resist film and the lens at the lowermost position of the exposure apparatus is pre-filled with a solvent (liquid immersion medium) that has a larger refractive index than the refractive index of air, and the exposure (immersion exposure) is carried out in this state.

The liquid immersion medium is preferably a solvent that exhibits a refractive index larger than the refractive index of air but smaller than the refractive index of the resist film to be exposed. The refractive index of such a solvent is not particularly limited as long as it is within the above-described range.

Examples of the solvent which exhibits a refractive index that is larger than the refractive index of air but smaller than the refractive index of the resist film include water, fluorine-based inert liquids, silicon-based solvents, and hydrocarbon-based solvents.

Specific examples of the fluorine-based inert liquids include liquids containing a fluorine-based compound such as C₃HCl₂F₅, C₄F₉OCH₃, C₄F₉OC₂H₅, or C₅H₃F₇ as the main component, and the boiling point is preferably in a range of 70° to 180° C. and more preferably in a range of 80° to 160° C. A fluorine-based inert liquid having a boiling point in the above-described range is advantageous in that removing the medium used in the liquid immersion after the exposure can be carried out by a simple method.

A fluorine-based inert liquid is particularly preferably a perfluoroalkyl compound obtained by substituting all hydrogen atoms of the alkyl group with a fluorine atom. Examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.

Further, specific examples of the perfluoroalkyl ether compound include perfluoro(2-butyl-tetrahydrofuran) (boiling point: 102° C.), and examples of the perfluoroalkyl amine compound include perfluorotributylamine (boiling point: 174° C.).

As the liquid immersion medium, water is preferable from the viewpoints of cost, safety, environment, and versatility.

Examples of the alkali developing solution used for a developing treatment in an alkali developing process include an aqueous solution in a range of 0.1% to 10% by mass of tetramethylammonium hydroxide (TMAH).

The organic solvent contained in the organic developing solution, which is used for a developing treatment in a solvent developing process may be any organic solvent capable of dissolving the component (A) (component (A) prior to exposure) and can be appropriately selected from the conventionally known organic solvents. Specific examples of the organic solvent include polar solvents such as a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, a nitrile-based solvent, an amide-based solvent, and an ether-based solvent, and hydrocarbon-based solvents.

A ketone-based solvent is an organic solvent containing C—C(═O)—C in the structure thereof. An ester-based solvent is an organic solvent containing C—C(═O)—O—C in the structure thereof. An alcohol-based solvent is an organic solvent containing an alcoholic hydroxyl group in the structure thereof. An “alcoholic hydroxyl group” indicates a hydroxyl group bonded to a carbon atom of an aliphatic hydrocarbon group. A nitrile-based solvent is an organic solvent containing a nitrile group in the structure thereof. An amide-based solvent is an organic solvent containing an amide group in the structure thereof. An ether-based solvent is an organic solvent containing C—O—C in the structure thereof.

Some organic solvents have a plurality of functional groups which characterize the above-described respective solvents in the structure thereof. In such a case, the organic solvent can be classified as any type of solvent having a characteristic functional group. For example, diethyleneglycol monomethylether can be classified as an alcohol-based solvent or an ether-based solvent.

A hydrocarbon-based solvent consists of a hydrocarbon which may be halogenated and does not have any substituent other than the halogen atom. The halogen atom is preferably a fluorine atom.

Among the above, the organic solvent contained in the organic developing solution is preferably a polar solvent and more preferably a ketone-based solvent, an ester-based solvent, a nitrile-based solvent, or the like.

Examples of ketone-based solvent include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone, propylenecarbonate, γ-butyrolactone and methylamyl ketone (2-heptanone). Among these examples, the ketone-based solvent is preferably methylamyl ketone (2-heptanone).

Examples of the ester-based solvent include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethyl methoxyacetate, ethyl ethoxyacetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monophenyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate, 4-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, 2-ethoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentyl acetate, propylene glycol diacetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, ethyl carbonate, propyl carbonate, butyl carbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, and propyl-3-methoxypropionate. Among these, the ester-based solvent is preferably butyl acetate.

Examples of the nitrile-based solvent include acetonitrile, propionitrile, valeronitrile, and butyronitrile.

As desired, the organic developing solution may have a conventionally known additive blended. Examples of the additive include surfactants. The surfactant is not particularly limited, and for example, an ionic or non-ionic fluorine-based and/or a silicon-based surfactant can be used. The surfactant is preferably a non-ionic surfactant and more preferably a non-ionic fluorine surfactant or a non-ionic silicon-based surfactant.

In a case where a surfactant is blended, the amount of the surfactant to be blended is typically in a range of 0.001% to 5% by mass, preferably in a range of 0.005% to 2% by mass, and more preferably in a range of 0.01% to 0.5% by mass with respect to the total amount of the organic developing solution.

The developing treatment can be carried out by a conventionally known developing method. Examples thereof include a method in which the support is immersed in the developing solution for a predetermined time (a dip method), a method in which the developing solution is cast upon the surface of the support by surface tension and maintained for a predetermined time (a puddle method), a method in which the developing solution is sprayed onto the surface of the support (spray method), and a method in which a developing solution is continuously ejected from a developing solution ejecting nozzle and applied to a support which is scanned at a constant rate while being rotated at a constant rate (dynamic dispense method).

As the organic solvent contained in the rinse liquid used in the rinse treatment after the developing treatment in a case of a solvent developing process, an organic solvent hardly dissolving the resist pattern can be suitably selected and used, among the organic solvents mentioned as organic solvents that are used for the organic developing solution. In general, at least one kind of solvent selected from the group consisting of a hydrocarbon-based solvent, a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, an amide-based solvent, and an ether-based solvent is used. Among these, at least one kind of solvent selected from the group consisting of a hydrocarbon-based solvent, a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, and an amide-based solvent is preferable, at least one kind of solvent selected from the group consisting of an alcohol-based solvent and an ester-based solvent is more preferable, and an alcohol-based solvent is particularly preferable.

The alcohol-based solvent used for the rinse liquid is preferably a monohydric alcohol of 6 to 8 carbon atoms, and the monohydric alcohol may be linear, branched, or cyclic. Specific examples thereof include 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, and benzyl alcohol. Among these, 1-hexanol, 2-heptanol, and 2-hexanol are preferable, and 1-hexanol and 2-hexanol are more preferable.

As the organic solvent, one kind of solvent may be used alone, or two or more kinds of solvents may be used in combination. Further, an organic solvent other than the above-described examples or water may be mixed thereto. However, in consideration of the development characteristics, the amount of water to be blended in the rinse liquid is preferably 30% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and most preferably 3% by mass or less with respect to the total amount of the rinse liquid.

A conventionally known additive can be blended with the rinse liquid as necessary. Examples of the additive include surfactants. Examples of the surfactant include the same ones as those described above, the surfactant is preferably a non-ionic surfactant and more preferably a non-ionic fluorine surfactant or a non-ionic silicon-based surfactant.

In a case where a surfactant is blended, the amount of the surfactant to be blended is typically in a range of 0.001% to 5% by mass, preferably in a range of 0.005% to 2% by mass, and more preferably in a range of 0.01% to 0.5% by mass with respect to the total amount of the rinse liquid.

The rinse treatment (the washing treatment) using a rinse liquid can be carried out by a conventionally known rinse method. Examples of the rinse treatment method include a method (a rotational coating method) in which the rinse liquid is continuously applied to the support while rotating it at a constant rate, a method (dip method) in which the support is immersed in the rinse liquid for a predetermined time, and a method (spray method) in which the rinse liquid is sprayed onto the surface of the support.

According to the method of forming a resist pattern according to the present embodiment described above, since the resist composition according to the embodiment described above is used, it is possible to form a resist pattern that has good sensitivity, good resolution, and good roughness reducing property.

EXAMPLES

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

Synthesis Example 1 Synthesis Example of Polymeric Compound (A1-1)

5.9 g of a monomer (a01-1m-01), 2.2 g of a monomer (a10-1-1 pre), and 0.5 g of azobis (isobutyric acid) dimethyl (V-601) as a polymerization initiator were dissolved in 30 g of methyl ethyl ketone (MEK), and the mixture was heated to 70° C. in a nitrogen atmosphere and stirred for 5 hours. Then, the reaction solution was cooled to room temperature.

Next, 2.0 g of acetic acid and 60 g of methanol were added to the obtained polymerization solution, and a deprotection reaction was carried out at 30° C. for 8 hours. After completion of the reaction, the obtained reaction solution was precipitated in 1,200 g of a mixed solvent of methanol and water and washed. The obtained white solid substance was filtered and dried under reduced pressure overnight to obtain the target polymeric compound (A1-1).

As a result of a GPC measurement to determine the weight average molecular weight (Mw) in terms of polystyrene equivalent value, the obtained polymeric compound (A1-1) had a weight average molecular weight of 6,500 and a polydispersity (Mw/Mn) of 1.57. The copolymerization compositional ratio (the ratio (the molar ratio) between constitutional units each derived from the monomer) determined by ¹³C-NMR was 1/m=70/30.

Synthesis Examples 2 to 20 of Polymeric Compounds

Polymeric compounds (A1-2) to (A1-18), (A2-1), and (A2-2) having compositional ratios shown in Table 1 were synthesized in the same manner as in Synthesis Example 1 of polymeric compound by using compounds (a01-1m-02) to (a01-1m-12) shown below and compounds each represented by General Formulae (a10-1-1 pre), (a10-1-2 pre), (a2-1m), (a3-1m), (a8-1m), and (a1-1m) to (a1-3m) shown below.

Regarding the obtained polymeric compounds, the copolymerization compositional ratio (the ratio (molar ratio) of the constitutional unit derived from each monomer) of the polymeric compound, which was determined by ¹³C-NMR, the weight average molecular weight (Mw) in terms of polystyrene equivalent value, which was determined by GPC measurement, and the polydispersity (Mw/Mn) are shown together in Table 1.

The constitutional units represented by Chemical Formula (a10-1-1) and the constitutional unit represented by Chemical Formula (a10-1-2), which constitute the above-described copolymer, are each constitutional units derived from a monomer represented by Chemical Formula (a10-1-1 pre) and a constitutional unit derived from a monomer represented by Chemical Formula (a10-1-2 pre).

TABLE 1 Weight- average Polymeric Copolymerization compositional ratio (molar ratio) molecular Polydispersity compound in polymeric compound (Mw) (Mw/Mn) Synthesis Example 1 (A1-1) l(a01-1m-01)/m(a10-1-1pre) = 70/30 6500 1.57 Synthesis Example 2 (A1-2) l(a01-1m-02)/m(a10-1-1pre) = 70/30 6700 1.55 Synthesis Example 3 (A1-3) l(a01-1m-03)/m(a10-1-1pre) = 70/30 6800 1.52 Synthesis Example 4 (A1-4) l(a01-1m-04)/m(a10-1-1pre) = 70/30 7000 1.54 Synthesis Example 5 (A1-5) l(a01-1m-05)/m(a10-1-1pre) = 70/30 6800 1.56 Synthesis Example 6 (A1-6) l(a01-1m-06)/m(a10-1-1pre) = 70/30 6300 1.62 Synthesis Example 7 (A1-7) l(a01-1m-07)/m(a10-1-1pre) = 70/30 6500 1.55 Synthesis Example 8 (A1-8) l(a01-1m-08)/m(a10-1-1pre) = 70/30 6200 1.59 Synthesis Example 9 (A1-9) l(a01-1m-09)/m(a10-1-1pre) = 70/30 6800 1.56 Synthesis Example 10 (A1-10) l(a01-1m-10)/m(a10-1-1pre) = 70/30 7100 1.61 Synthesis Example 11 (A1-11) l(a01-1m-11)/m(a10-1-1pre) = 70/30 7300 1.63 Synthesis Example 12 (A1-12) l(a01-1m-02)/m(a10-1-2pre) = 70/30 5900 1.61 Synthesis Example 13 (A1-13) l(a01-1m-02) = 100 6400 1.57 Synthesis Example 14 (A1-14) l(a01-1m-02)/m(a10-1-1pre)/n(a2-1m) = 70/20/10 7300 1.58 Synthesis Example 15 (A1-15) l(a01-1m-02)/m(a10-1-1pre)/n(a8-1m) = 70/20/10 6800 1.59 Synthesis Example 16 (A1-16) l(a01-1m-02)/m(a2-1m)/n(a3-1m) = 80/10/10 6800 1.56 Synthesis Example 17 (A1-17) l(a01-1m-02)/m(a1-1m) = 80/20 6900 1.55 Synthesis Example 18 (A2-1) l(a1-2m)/m(a10-1-1pre) = 70/30 7200 1.62 Synthesis Example 19 (A2-2) l(a1-3m)/m(a10-1-1pre) = 70/30 6300 1.58 Synthesis Example 20 (A1-18) l(a01-1m-12)/m(a10-1-1pre) = 70/30 7600 1.57

Preparation of Resist Composition

Examples 1 to 32 and Comparative Examples 1 to 5

Each of the components shown in Tables 2 to 6 was mixed and dissolved to prepare a resist composition of each Example.

TABLE 2 Component Component Component Component (A) (B) (D) (S) Example 1 (A1)-1 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 2 (A1)-2 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 3 (A1)-3 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 4 (A1)-4 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 5 (A1)-5 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 6 (A1)-6 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 7 (A1)-7 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 8 (A1)-8 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 9 (A1)-9 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 10 (A1)-10 (B01)-1 (D)-1 (S)-1 [100  [24] [5.0] [6400] Example 11 (A1)-11 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 12 (A1)-12 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 13 (A1)-13 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 14 (A1)-14 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 15 (A1)-15 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 16 (A1)-16 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 17 (A1)-17 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400] Example 18 (A1)-2 (B01)-1 (D)-2 (S)-1 [100] [24] [5.8] [6400] Example 19 (A1)-5 (B01)-1 (D)-2 (S)-1 [100] [24] [5.8] [6400]

TABLE 3 Component Component Component Component (A) (B) (D) (S) Comparative (A2)-1 (B01)-1 (D)-1 (S)-1 Example 1 [100] [24] [5.0] [6400] Comparative (A2)-2 (B01)-1 (D)-1 (S)-1 Example 2 [100] [24] [5.0] [6400]

TABLE 4 Component Component Component Component (A) (B) (D) (S) Example 20 (A1)-2 (B01)-2 (D)-1 (S)-1 [100] [22.0] [5.0] [6400] Example 21 (A1)-2 (B01)-3 (D)-1 (S)-1 [100] [24.7] [5.0] [6400] Example 22 (A1)-2 (B01)-4 (D)-1 (S)-1 [100] [24.4] [5.0] [6400] Example 23 (A1)-2 (B01)-5 (D)-1 (S)-1 [100] [32.1] [5.0] [6400] Example 24 (A1)-2 (B01)-6 (D)-1 (S)-1 [100] [26.5] [5.0] [6400] Example 25 (A1)-2 (B01)-7 (D)-1 (S)-1 [100] [23.2] [5.0] [6400] Example 26 (A1)-2 (B01)-8 (D)-1 (S)-1 [100] [22.4] [5.0] [6400] Example 27 (A1)-2 (B02)-1 (D)-1 (S)-1 [100] [23.5] [5.0] [6400]

TABLE 5 Component Component Component Component (A) (B) (D) (S) Comparative (A1)-2 (B1)-10 (D)-1 (S)-1 Example 3 [100] [21.5] [5.0] [6400] Comparative (A1)-2 (B1)-11 (D)-1 (S)-1 Example 4 [100] [19.5] [5.0] [6400] Comparative (A1)-2 (B1)-12 (D)-1 (S)-1 Example 5 [100] [21.1] [5.0] [6400]

TABLE 6 Component Component Component Component (A) (B) (D) (S) Example 28 (A1)-2 (B01)-9 (D)-1 (S)-1 [100]   [35.7] [5.0] [6400] Example 29 (A1)-2  (B01)-10 (D)-1 (S)-1 [100]   [28.4] [5.0] [6400] Example 30 (A1)-2 (B01)-1 (D)-3 (S)-1 [100] [24] [9.5] [6400] Example 31 (A1)-2 (B01)-1 (D)-4 (S)-1 [100] [24] [8.8] [6400] Example 32 (A1)-18 (B01)-1 (D)-1 (S)-1 [100] [24] [5.0] [6400]

In Tables 2 to 6, each abbreviation has the following meaning. The numerical values in the brackets are blending amounts (parts by mass).

(A1)-1 to (A1)-18: the polymeric compounds (A1-1) to (A1-18).

(A2)-1 and (A2)-2: the polymeric compounds (A2-1) and (A2-2).

(B01)-1 to (B01)-10: acid generators consisting of compounds each represented by Chemical Formulae (B01-1) to (B01-10).

(B02)-1: an acid generator consisting of a compound represented by Chemical Formula (B02-1).

(B2)-1 to (B2)-3: acid generators consisting of compounds each represented by Chemical Formulae (B2-1) to (B2-3).

(D)-1 to (D)-4: acid diffusion controlling agents consisting of compounds each represented by Chemical Formulae (D-1) to (D-4).

(S)-1: a mixed solvent of propylene glycol monomethyl ether acetate/propylene glycol monomethyl ether= 60/40 (mass ratio)

<Formation of Resist Pattern>

The resist composition of each Example was applied onto an 8-inch silicon substrate which had been subjected to a hexamethyldisilazane (HMDS) treatment using a spinner, the coated wafer was subjected to a post-apply baking (PAB) treatment on a hot plate at a temperature of 110° C. for 60 seconds so that the coated wafer was dried to form a resist film having a film thickness of 50 nm.

Next, drawing (exposure) was carried out on the resist film by using an electron beam lithography apparatus JEOL-JBX-9300FS (manufactured by JEOL Ltd.), with the target size being set to a 1:1 line and space pattern (hereinafter, referred to as an “LS pattern”) of a line width of 50 nm, at an acceleration voltage of 100 kV. Thereafter, a post-exposure baking (PEB) treatment was carried out on the resist film at 90° C. for 60 seconds.

Subsequently, alkali development was carried out at 23° C. for 60 seconds using a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution “NMD-3” (product name, manufactured by TOKYO OHKA KOGYO CO., LTD.).

Thereafter, rinsing was carried out with pure water for 15 seconds.

As a result of the above, a 1:1 LS pattern having a line width of 50 nm was formed.

[Evaluation of Optimum Exposure Amount (Eop)]

According to <Formation of resist pattern> described above, an optimum exposure amount Eop (μC/cm²) for forming the LS pattern having the target size was determined. The results are shown in Tables 7 to 11 as “Eop (μC/cm²)”.

[Evaluation of Limiting Resolution]

LS patterns were formed by gradually increasing the exposure amount from the optimum exposure amount Eop described above, and the limiting resolution at the above Eop, specifically, the minimum size of the pattern that was resolved without being collapsed were determined using a scanning electron microscope S-9380 (manufactured by Hitachi High-Tech Corporation). The results are shown in Tables 7 to 11 as “Limiting resolution (nm)”.

[Evaluation of Linewise Roughness (LWR)]

3σ of the LS pattern formed in <Formation of resist pattern> described above, which is a scale indicating LWR, was determined. The results are shown in Tables 7 to 11 as “LWR (nm)”.

“3σ” indicates a triple value (unit: nm) of the standard deviation (o) determined from measurement results obtained by measuring 400 line positions in the longitudinal direction of the line with a scanning electron microscope (acceleration voltage: 800V, product name: S-9380, manufactured by Hitachi High-Tech Corporation).

The smaller the value of 3σ is, the smaller the roughness in the line side wall is, which means an LS pattern having a more uniform width was obtained.

TABLE 7 Limiting PAB PEB Eop resolution LWR (° C.) (° C.) [μC/cm²] [nm] [nm] Example 1 110 90 124 36 5.5 Example 2 110 90 117 32 5.4 Example 3 110 90 116 32 5.6 Example 4 110 90 112 36 5.3 Example 5 110 90 110 32 5.2 Example 6 110 90 119 32 5.5 Example 7 110 90 113 32 5.6 Example 8 110 90 118 32 5.5 Example 9 110 90 116 32 5.6 Example 10 110 90 110 32 5.3 Example 11 110 90 119 36 5.7 Example 12 110 90 113 36 5.9 Example 13 110 90 121 32 5.4 Example 14 110 90 116 32 5.7 Example 15 110 90 115 32 5.6 Example 16 110 90 118 32 5.8 Example 17 110 90 124 32 5.4 Example 18 110 90 114 32 5.0 Example 19 110 90 105 32 4.9

TABLE 8 Limiting PAB PEB Eop resolution LWR (° C.) (° C.) [μC/cm²] [nm] [nm] Comparative 110 90 142 40 6.8 Example 1 Comparative 110 90 144 40 6.7 Example 2

TABLE 9 Limiting PAB PEB Eop resolution LWR (° C.) (° C.) [μC/cm²] [nm] [nm] Example 20 110 90 116 32 5.6 Example 21 110 90 113 32 5.3 Example 22 110 90 115 36 5.4 Example 23 110 90 107 32 5.1 Example 24 110 90 105 32 5.0 Example 25 110 90 119 36 5.9 Example 26 110 90 117 36 6.1 Example 27 110 90 110 32 5.3

TABLE 10 Limiting PAB PEB Eop resolution LWR (° C.) (° C.) [μC/cm²] [nm] [nm] Comparative 110 90 128 32 6.9 Example 3 Comparative 110 90 132 32 6.8 Example 4 Comparative 110 90 131 36 7.3 Example 5

TABLE 11 Limiting PAB PEB Eop resolution LWR (° C.) (° C.) [μC/cm²] [nm] [nm] Example 28 110 90 102 32 5.1 Example 29 110 90 104 32 5.4 Example 30 110 90 114 32 5.3 Example 31 110 90 112 32 5.3 Example 32 110 90 115 32 5.5

As shown in Tables 7 to 11, it has been confirmed that it is possible to form a resist pattern that has good sensitivity, good resolution, and good roughness reducing property with the resist compositions of Examples as compared with the resist compositions of Comparative Examples.

Specifically, as shown in Tables 7 and 8, it has been confirmed that in a case where the same acid generator (the compound (B01-1)) is used, it is possible to form a resist pattern that has good sensitivity, good resolution, and good roughness reducing property with the resist compositions of Examples 1 to 19, which contain the resin component (A1) having the constitutional unit (a01), as compared with the resist compositions of Comparative Examples 1 and 2, which contain a resin component having no constitutional unit (a01).

In addition, from the comparison between the resist composition of Example 2 and the resist composition of Example 18, and the comparison between the resist composition of Example 5 and the resist composition of Example 19, it has been confirmed it is possible to form a resist pattern that has better sensitivity and better roughness reducing property with the resist compositions of Examples 18 and 19, which have a fluorine atom in the cation moiety of the acid diffusion controlling agent in addition to the acid generator component (B).

Further, as shown in Tables 9 and 10, it has been confirmed that in a case where the same resin component (the polymeric compound (A1-2)) is used, it is possible to form a resist pattern that has good sensitivity and good roughness reducing property with the resist compositions of Examples 2 and 20 to 27, which contain the compound (B01) or the compound (B02) as compared with the resist compositions of Comparative Examples 3 to 5, which contain the acid generator component (B) having no fluorine atom in the cation moiety.

While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the invention. Accordingly, the invention is not to be considered as being limited by the foregoing description and is only limited by the scope of the appended claims. 

What is claimed is:
 1. A resist composition that generates acid upon exposure and exhibits changed solubility in a developing solution under action of acid, the resist composition comprising: a resin component (A1) which exhibits changed solubility in a developing solution under action of acid; and an acid generator component (B) which generates an acid upon exposure, wherein the resin component (A1) has a constitutional unit (a01) derived from a compound represented by General Formula (a0-1), and the acid generator component (B) contains one or more compounds selected from the group consisting of a compound (B01) represented by General Formula (b0-1) and a compound (B02) represented by General Formula (b0-2):

wherein W⁰¹ represents a polymerizable group-containing group; Ya⁰¹ represents a single bond or a divalent linking group; Rx⁰¹ represents an acid dissociable group; q represents an integer in a range of 0 to 3, and n represents an integer of 1 or more, provided that n≤q×2+4 is satisfied,

wherein, in General Formula (b0-1), R^(b1) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group; R^(b2) and R^(b3) each independently represent an aryl group which may have a substituent, an alkyl group which may have a substituent, or an alkenyl group which may have a substituent; two of R^(b1) to R^(b3) may be bonded to each other to form a ring together with the sulfur atom in the formula; X₀₁ ⁻ represents a counter anion; in General Formula (b0-2), R^(b4) represents an aryl group having a fluorine atom or an aryl group having a fluorinated alkyl group; R^(b5) represents an aryl group which may have a substituent, an alkyl group which may have a substituent, or an alkenyl group which may have a substituent; and X₀₂ ⁻ represents a counter anion.
 2. The resist composition according to claim 1, wherein the constitutional unit (a01) is a constitutional unit represented by General Formula (a0-1-1):

wherein R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbon atoms; Ya⁰⁰¹ represents a single bond or a divalent linking group; Ya⁰¹ represents a single bond or a divalent linking group; Rax⁰¹ represents an acid dissociable group represented by General Formula (a0-r-1) or (a0-r-2); q represents an integer in a range of 0 to 3, and n represents an integer of 1 or more, provided that n≤q×2+4 is satisfied,

wherein, in General Formula (a0-r-1), Ra⁰¹ and Ra⁰² each independently represent a hydrogen atom or an alkyl group; Ra⁰³ represents a hydrocarbon group and may be bonded to any one of Ra⁰¹ or Ra⁰² to form a ring; and * represents a bonding site; and in General Formula (a0-r-2), Ra⁰⁴ to Ra⁰⁶ each independently represents a hydrocarbon group, provided that Ra⁰⁵ and Ra⁰⁶ may be bonded to each other to form a ring; and * represents a bonding site.
 3. The resist composition according to claim 1, wherein the compound (B01) represents a compound represented by General Formula (b0-1-1):

wherein R^(b2) and R^(b3) each independently represent an aryl group which may have a substituent, an alkyl group which may have a substituent, or an alkenyl group which may have a substituent; R^(b2) and R^(b3) may be bonded to each other to form a ring together with the sulfur atom in the formula; X⁰¹¹ represents a fluorine atom or a fluorinated alkyl group; R⁰¹¹ represents a substituent; nb represents an integer of 1 or more, pb represents an integer of 0 or more, and qb represents an integer in a range of 0 to 3, provided that, nb+pb≤qb×2+5 is satisfied; and X₀₁ ⁻ represents a counter anion.
 4. The resist composition according to claim 1, wherein a proportion of the constitutional unit (a01) in the resin component (A1) is 50% by mole or more based on 100% by mole of all constitutional units constituting the resin component (A1).
 5. The resist composition according to claim 1, wherein a content of the one or more compounds selected from the group consisting of the compound (B01) and the compound (B02) is in a range of 5 to 40 parts by mass with respect to 100 parts by mass of the resin component (A1).
 6. A method of forming a resist pattern, comprising: forming a resist film on a support using the resist composition according to claim 1; exposing the resist film; and developing the exposed resist film to form a resist pattern.
 7. The method of forming a resist pattern according to claim 6, wherein the resist film is exposed with an extreme ultraviolet ray (EUV) or an electron beam (EB). 